Alexsandr Kallus, a male human, began as a rebel spy during the Alliance to Restore the Republic's early days, continuing into the Galactic Civil War's initial stages. Once a dedicated agent and captain within the Imperial Security Bureau (ISB-021), Kallus deeply believed in the Galactic Empire and its mission to impose order upon the galaxy. He actively suppressed dissent across various planets, engaging against Saw Gerrera's insurgency on Onderon, participating in the genocide of Lasan, and spearheading the pursuit of the Ghost's rebels on Lothal. His efforts on Lothal were largely unsuccessful, which led to an increase of Imperial presence against the growing rebellion, including Grand Moff Wilhuff Tarkin, Governor of the Outer Rim Territories, and Darth Vader, the Emperor's Fist.
After chasing the Ghost crew for over one year, Kallus attempted to ensnare them in orbit around Geonosis. This confrontation resulted in Kallus and Garazeb Orrelios, a Lasat warrior from the Ghost, being stranded on the frozen moon of Bahryn. Working together for survival, they discovered a shared understanding as soldiers, and Kallus began to re-evaluate his convictions about the Empire and the rebellion, after learning about the rebels and their camaraderie. Consequently, with Zeb's help, he secretly became a rebel informant known as Fulcrum. He supplied the rebellion with intelligence concerning Imperial operations, including those of Grand Admiral Thrawn, who was tasked with quelling the rebels in the Lothal sector.
Thrawn unmasked Kallus's true allegiance after deducing the existence of a rebel spy within his ranks. Kallus was apprehended while trying to transmit information to the rebels regarding their planned assault on Lothal. Ultimately, Thrawn discovered the rebel base located on Atollon and initiated an attack that severely weakened the rebellion. During the battle, Kallus escaped from Imperial custody and was rescued by the Ghost. He then accompanied the surviving rebels to the base on Yavin 4, thereby avoiding certain death.
Fully integrated into the Rebellion, Kallus provided both tactical assistance and battlefield support to the Alliance. As a crucial ally of the Ghost crew, he played a role in the successful liberation of Lothal. Following the Empire's defeat in 4 ABY and the subsequent conclusion of the Galactic Civil War in 5 ABY, Orrelios escorted Kallus to Lira San, the ancestral home of the Lasat people, to demonstrate that the Lasat species had survived, contrary to Kallus's past actions. As a comrade to Orrelios who had turned against his former Empire, Kallus was welcomed by the Lasat as one of their own.

Born on Coruscant during the twilight of the Galactic Republic, between 44 BBY and 35 BBY, Alexsandr Kallus was a male human. After Darth Sidious, a Sith Lord known publicly as Supreme Chancellor Palpatine, proclaimed himself Emperor and converted the Republic into the Galactic Empire, Kallus enrolled in the Royal Imperial Academy on Coruscant, which served as the primary campus for the new regime's military training program. At the Academy, Kallus studied under Wullf Yularen, who regarded him as a top student. He also developed a friendship with Jovan, who acted as an informal mentor to the young Coruscanti. Eventually, they both finished their studies, with Kallus graduating at the top of his class. Sometime after this, Kallus became a member of the Imperial Security Bureau, a clandestine organization dedicated to suppressing rebellious activities throughout the galaxy. Designated ISB-021, Kallus ascended to become a high-ranking ISB Agent and captain, serving in the Enforcement, Internal Affairs, and Investigations divisions of the bureau.
Following his graduation, Kallus's first command was leading his own squad of stormtroopers. Around 18 BBY, Kallus and his squad were dispatched by the Empire to restore order to Onderon as Kallus's inaugural mission. The planet had descended into chaos in the aftermath of the Clone Wars. During a routine patrol led by Kallus, a rebel mercenary, a Lasat working for Saw Gerrera, ambushed the squad and incapacitated Kallus. Upon regaining consciousness, the ISB agent found himself unable to move and was forced to witness the brutal murder of his squad by the Lasat mercenary, instilling in Kallus a deep-seated hatred for the Lasat species. Despite this, the Lasat spared Kallus's life, leaving the Imperial perplexed. Kallus later encountered fellow ISB agent Andressa Divo and discussed at length the violent aspects of Gerrera's campaigns, which disturbed Divo to the point that she hesitated to include precise details in her personal reports.

Around 10 BBY, Kallus collaborated with IG-88 in the pursuit of Captain Han Solo of the Millennium Falcon, a smuggler who had deserted from the Imperial Army. Kallus used a shuttle to locate Solo during one of his smuggling operations. After discovering Solo's aid to Enfys Nest on Savareen, Kallus declared Solo an enemy of the Empire. Suspecting Solo of smuggling items to Nest, he instructed IG-88 to inspect Solo's cargo. However, Solo's co-pilot, Chewbacca, attacked Kallus and IG-88. Although Solo and Chewbacca managed to escape, Kallus and IG-88 returned to the shuttle. Kallus ordered two Star Destroyers to block the Falcon's path. Nevertheless, the Falcon navigated between the two Star Destroyers and escaped. Kallus was astonished by Solo's recklessness.
Kallus participated in the cleansing of Lasan in 7 BBY. The planet was the homeworld of the Lasat, the species Kallus despised due to the mercenary's actions that had destroyed his first unit years prior. The battle resulted in the near-extinction of the Lasat species, who were completely expelled from their homeworld. Before the cleansing of Lasan concluded, Kallus received a J-19 bo-rifle from a member of the Lasan High Honor Guard whom he had defeated, a gift that surprised and deeply affected Kallus. Unbeknownst to the Imperial agent at the time, this was the Lasat way of Boosahn Keeraw.
Kallus later claimed to have ordered Imperial troops to use T-7 ion disruptor rifles against the population, but he later admitted that this was a lie intended to taunt Garazeb Orrelios. These rifles possessed the capability to disable starships and caused horrific damage when used against sentient beings. The Imperial Senate ultimately banned these weapons due to their destructive power.
Five years prior to the Battle of Yavin, a rebel cell was operating on Lothal, attacking various Imperial targets. These actions attracted the attention of the Imperial Security Bureau, which dispatched Kallus to Lothal to address the situation. He arrived aboard a shuttle and requested permission to dock with the Lawbringer, an Imperial I-class Star Destroyer orbiting the planet. Captain Hiram Zataire granted Kallus permission to dock, and they later dined together aboard the Lawbringer. Kallus's objective during the meal was to assess Zataire's loyalty as an Imperial officer. They discussed Zataire's son, an outspoken critic of the Empire, after Kallus deduced that the wine the captain served him was from Alderaan—a planet the Empire considered rebellious—and that it had been given to the captain as a gift by his son. This revelation allowed Kallus to determine that Zataire's son was on Alderaan, providing the ISB with an opportunity to arrest him. Zataire pleaded with Kallus not to harm his son. The ISB Agent stated that the law allowed him flexibility as long as Captain Zataire fully cooperated with Kallus's operations on Lothal, a request that the captain accepted. Kallus's first order to the captain was to have the Lawbringer descend from orbit and hover over Capital City, allowing the citizens of Lothal to witness the Empire's might.

As the Lawbringer hovered over the capital, the rebels launched an operation against the Empire, stealing crates of blasters and food. That night, Kallus inspected the damage caused by the Empire. Commandant Cumberlayne Aresko, one of the leading military officers on Lothal, briefed him on the attack. Kallus explained that it was part of a pattern that, if unchecked, could lead to a larger rebel movement.
To eliminate the rebels, Kallus devised a trap by making them believe they had discovered the location of Wookiee slaves held by the Empire. Although the Empire did hold Wookiee prisoners, the rebels were given false information regarding their location. The Ghost docked with a Gozanti-class cruiser that the rebels believed contained the slaves. Jedi survivor Kanan Jarrus, Lasan High Honor Guardsman Garazeb Orrelios, Mandalorian warrior Sabine Wren, and the droid C1-10P boarded the ship, while the Lawbringer emerged from hyperspace and captured the Gozanti-class cruiser and the Ghost. With the ships secured, Kallus and his stormtroopers boarded the cruiser and attacked the rebels. Wren and the droid deactivated the gravity generator on the ship, surprising the Imperials and allowing the rebels to escape. During the escape, Kallus captured Ezra Bridger, a new member of the Ghost crew who had boarded to warn the rebels of the Lawbringer's arrival.
With Bridger in custody, Kallus planned to use the boy to lure the rebels back, believing they would attempt a rescue. Kallus spoke to Bridger in his cell and revealed the plan, but Bridger doubted that the Ghost would return, as he had never witnessed anyone risking their lives for others. Despite Bridger's skepticism, the rebels did return, although the boy escaped from his holding cell on his own. The Ghost landed in the lower hangar, which the Imperials detected. Kallus ordered all stormtroopers to converge on the lower hangar, where he would meet them, while diverting some to the upper hangar. Bridger, who was listening to Imperial communications through a stolen stormtrooper helmet, posed as a stormtrooper and suggested that the lower hangar could be a diversion.

Kallus led his stormtroopers to the lower hangar, where he discovered that Bridger had rejoined the rebels. The rebels fled upon seeing the Imperial troops, who pursued them and fired on the Ghost. As the rebel ship prepared to depart, Kallus noticed graffiti art on the hangar floor, drawn by Wren, and realized it was an explosive. He ordered his men to take cover, but the explosion ripped through the hangar, injuring some of his men. Kallus survived, thrown forward by the explosion. The damage caused a hull breach, and many stormtroopers were blown into space. Kallus himself was nearly pulled into space as well, but he held onto the hangar deck until a force field sealed the hull breach. He remained in the hangar as the Imperials recovered from the rebel attack and was brought the helmet that Bridger stole and left behind, prompting the ISB Agent to realize that Bridger had overheard that the true location of the Wookiee prisoners was the spice mines of Kessel.
Knowing that the rebels would seize the opportunity to rescue the Wookiees, Kallus allowed them to reach Kessel, where they freed the Wookiee slaves from the Imperial forces stationed in spice mine K76. Before the rebels could escape, Kallus and additional Imperial forces arrived, firing on the Ghost and forcing it to flee while the rest of the rebels remained in the mine. Kallus and a squadron of stormtroopers landed at the mine and advanced on the rebels, forcing them to take cover. With the rebels pinned down, the rebel leader, Jarrus, stepped forward and ignited his lightsaber, revealing himself as a Jedi who had survived the destruction of the Jedi Order. Kallus ordered his soldiers to focus their fire on Jarrus, allowing the rest of the rebels and the Wookiees to enter a cargo container that would be picked up by the Ghost upon its return.

While the stormtroopers focused on the rebels, Kallus pursued Bridger to a walkway overlooking the mine, where the boy had gone to rescue Kitwarr, a young Wookiee who had escaped and was being chased by a stormtrooper. Kallus arrived to witness Bridger attacking the stormtrooper with an energy slingshot, knocking the trooper over the railing. Believing Bridger to be Jarrus's apprentice, Kallus prepared to kill the boy, but the Ghost arrived to rescue Bridger. Jarrus, standing atop the ship, deflected Kallus's fire back at the ISB Agent. Kallus was struck by blaster fire, knocking him over the railing, which he clung to as the Ghost escaped. The stormtrooper, who had also fallen over, clung to the railing as well and asked if Jarrus was the first Jedi that Kallus had ever seen. In response, Kallus kicked the trooper off the railing, sending him falling into the mines.
Kallus departed the spice mines and returned to the Lawbringer, which remained in orbit over Kessel. From the ship, Kallus contacted the Grand Inquisitor, a dark side warrior tasked with hunting down Jedi survivors. Kallus informed the Inquisitor, who appeared via hologram, about the events on Kessel and that the leader of the rebel cell was a Jedi, to which the Inquisitor acknowledged Kallus's good work in informing him.
Following their successful rescue of the Wookiees, the rebels embarked on a mission to steal T-7 ion disruptor rifles from Garel. It was there that Minister Maketh Tua of Lothal was attempting to acquire the illegal weapons from Amda Wabo, an Aqualish weapons manufacturer. The rebels secured the disruptors before the Imperials could, thwarting the arms deal and taking the weapons for themselves, along with two droids, R2-D2 and C-3PO, who were part of the arms deal on orders of Governor Arihnda Pryce of Lothal and who were covertly working for the secretly rebellious Senator Bail Organa of Alderaan. After the rebels stole the weapons, Tua contacted Agent Kallus and informed him of the events on Garel, which Kallus recognized as the work of the Ghost crew. C-3PO, believing himself to be the prisoner of criminals, attempted to send a distress signal to Governor Pryce, but the signal was rerouted and intercepted by Kallus aboard the Lawbringer. C-3PO provided Kallus with the location of the Ghost, and Kallus deceived the droid by telling him that help was on the way.

The rebels returned to Lothal, intending to sell the disruptors to the Devaronian crime lord Cikatro Vizago. Before the deal could be completed, Kallus and his forces arrived in Imperial Troop Transports, accompanied by All Terrain Defense Pods. While the stormtroopers and AT-DPs engaged most of the rebels, Kallus challenged Orrelios to single combat with bo-rifles. The enraged Lasat accepted the ISB Agent's challenge, and the two fought while the rebels battled the Imperial forces and destroyed the disruptors. By the end of their duel, during which Kallus taunted Orrelios about the fall of Lasan, Orrelios was nearly defeated. Kallus attempted a fatal blow, but Bridger intervened, using the Force to push Kallus away. This allowed the rebels to escape, leaving Kallus to watch the Ghost fly away.

Some time passed before the rebels devised a strategy to enter secretly the Academy for Young Imperials located on Lothal. Their objective was to pilfer a cipher from Kallus' office inside the Academy. This cipher was crucial for pinpointing the whereabouts of an immensely powerful kyber crystal, which the rebels aimed to obliterate. Bridger took on the role of infiltration, adopting the guise of a cadet named Dev Morgan. After spending several weeks within the facility, Bridger initiated his plan to discreetly enter Kallus' office. Upon his arrival, he observed Kallus departing from his office. Bridger, having emerged victorious in a cadet tournament, secured the position of an aide within the Imperial Complex. He arrived, concealing his identity with a helmet, carrying a datapad that he was tasked to deliver. The rebel offered to leave the datapad on the ISB Agent's desk, but Kallus opted to take it himself and departed from the area. Once Kallus had left, Bridger made his way into the office, only to be intercepted by fellow cadet Zare Leonis, who was aware that the theft would trigger an alarm. Given that Leonis also harbored anti-Imperial sentiments, the two united and decided to steal the cipher together.
The following day, the two rebels put their plan into action. Bridger stealthily navigated through a ventilation shaft to access Kallus' office from above. Simultaneously, Leonis requested authorization to enter Kallus' office. The cadet informed Kallus that the Agent's podracer components had been delivered. Kallus questioned the order, stating that he had neither requested nor required any podracer parts. Leonis insisted that the parts were intended for Kallus, effectively stalling the Agent and providing Bridger with the necessary time to steal the cipher. Bridger employed the Force to levitate the decoder, causing it to float towards the opening of the ventilation shaft. Kallus noticed Leonis' startled reaction to the use of the Force and turned around, but Bridger had already completed the theft before the Agent could detect him. Leonis inquired once more whether he would be signing for the podracer parts, but Kallus declined, asserting that it was a mistake.
As Bridger retraced his steps through the vents, he discovered that he and another cadet, Jai Kell, had demonstrated skills that piqued the interest of the Inquisitor, who was scheduled to arrive on Lothal the following day to assess them. Consequently, Bridger, Leonis, and Kell orchestrated an escape from the Academy. Leonis, however, remained behind, as he had unresolved matters at the Academy. He feigned an attempt to prevent the rebels from escaping to avoid raising suspicion. Upon the Inquisitor's arrival, Kallus was present and received information about the escape. The Inquisitor identified "Cadet Morgan" as Bridger, recalling their previous encounter on Stygeon Prime, which confirmed that Bridger's presence was an act of infiltration.

Following the incident at the Academy, Agent Kallus was assigned the task of apprehending his former companion and mentor, Jovan. Jovan had exploited his position as an Imperial lieutenant on Ganthel to amass personal wealth. Kallus successfully located Jovan in the small Lothalian town of Dinar. The two engaged in a skirmish within an alleyway. Jovan managed to escape, commandeering a stolen TIE starfighter, but Kallus pursued him across the plains of Lothal in another fighter. Despite being a less skilled pilot than his former acquaintance, the ISB agent managed to bring down the rogue lieutenant by employing a maneuver that he had learned from him during their amicable past. Defeated, Jovan implored Kallus to release him out of respect for their shared history, but the agent refused to allow his personal sentiments to override his allegiance to the Empire. Kallus then returned to the Imperial headquarters on Lothal while his former friend was taken to prison.

The Imperial authorities on Lothal orchestrated a series of celebrations for Empire Day, commemorating the fifteenth anniversary of the Clone Wars' conclusion and the Galactic Empire's establishment. On Empire Day, the local administration also initiated a search for a Rodian named Tseebo, who had stolen critical data from the Imperial Information Office where he was employed. Kallus participated in the Rodian's pursuit, even during the Empire Day parade in Capital City. During the parade, the rebels destroyed an experimental TIE Advanced v1 starfighter. Following their escape from the scene, Kallus assumed command of the investigation to locate them and requested schematics of the city's ventilation systems, sewers, and other potential hiding places for the rebels. Minister Tua demanded that the rebels face punishment for disrupting Empire Day, and Kallus assured her of his desire to punish them, but emphasized that their primary objective remained the apprehension of Tseebo.
Having fled the scene of the attack, the rebels sought refuge at Ezra Bridger's childhood home, where they discovered Tseebo in hiding. Tseebo had been a friend of Bridger's parents before their disappearance several years prior. The rebels examined the information that Tseebo had stolen and resolved to extract him from the planet to analyze the secrets he possessed. To facilitate his departure from the city, the rebels hijacked an Imperial Troop Transport. Kallus learned of the hijacking and contacted Commandant Aresko, who had established a blockade at the city's perimeter, to warn him of the approaching rebels. Nevertheless, the rebels breached the blockade and escaped to the city's outskirts.
Kallus arrived in his own ITT and pursued the rebels out of the city. During the pursuit, Kallus contacted the Inquisitor to inform him that the rebels had breached the main city gate and were heading south. The Inquisitor, who was boarding his personal TIE Advanced fighter, suspected that the Ghost would be waiting and instructed Kallus to impede their escape. Kallus' men created a breach in the hijacked ITT and attempted to board it, while Kallus' ITT continued firing. Kallus ascended to the roof of his ITT and leaped onto the rebels' ITT just as the Ghost arrived. Orrelios fired at Kallus, aiming to end their ongoing conflict, as Kallus ordered his ITT to fire on the Ghost. The Ghost, in turn, destroyed Kallus' ITT. Orrelios, having missed his initial shot, fired again at Kallus, causing him to fall from the side of the rebels' ITT—though he managed to cling to the vehicle's rear.

The rebels initiated their escape onto the Ghost, heading to the stolen ITT's roof to quickly board the ship. Kallus climbed back atop the ITT in time to witness Tseebo stepping onto the ramp that the Ghost had lowered. He fired towards the rebels, prompting Jarrus to ignite his lightsaber and confront the ISB Agent. The Jedi deflected Kallus' blasts before boarding the Ghost, which departed to escape Lothal. As it was leaving, Kallus contacted the Inquisitor to confirm that Tseebo was aboard the rebel ship. The Inquisitor and his fighters pursued the rebels off of Lothal, but ultimately failed to stop them or capture Tseebo.
Following the rebel attack on the Empire Day celebrations, Governor Arihnda Pryce mandated a planet-wide crackdown on sedition and dissent. Agent Kallus was placed in command of the crackdown, and all military personnel on Lothal, including Imperial cadets, were conscripted to participate. Under Kallus' directives, Imperial cadets were tasked with questioning residents about illegal activities in their neighborhoods, apprehending criminals, detaining the children of fugitives, and leading stormtroopers on law enforcement raids. Kallus' stringent stance on crime and orders to detain children horrified some Imperials, such as Cadet Zare Leonis and Lieutenant Chiron, but they refrained from openly defying his orders, as the crackdown had the backing of the governor and all Imperial ministries on Lothal.
Recognizing that the rebels routinely stole food supplies from the Empire, Kallus resolved to exploit this pattern. The agent tampered with the supplies and allowed the rebels to capture them, ensuring that their contents would poison anyone who consumed them. As anticipated, several residents of the refugee settlement of Tarkintown ingested the poisoned food and became ill, prompting Garazeb Orrelios to independently raid the Imperial compound in search of an antidote. Upon Orrelios' arrival at the medical facility, Kallus awaited him with four stormtroopers. The ISB agent engaged in a duel with the Lasat, gaining the upper hand for a period. However, the situation shifted when Hera Syndulla, Kanan Jarrus, Sabine Wren, and Ezra Bridger arrived to rescue their friend, overpowering the Imperials and successfully escaping the compound.

Having failed to thwart the rebels on Empire Day, Kallus formulated a strategy to lure them into a trap and eliminate them. The plan involved Senator Gall Trayvis, who covertly worked for the Empire by posing as a dissident voice to monitor and lure rebel forces across the galaxy into ambushes. Trayvis disseminated a message via a hacked HoloNet News transmission, stating that he would meet the rebels in the Lothal City Capitol Building on Lothal. The rebels took the bait, and Kallus prepared the trap, although Minister Tua questioned its potential effectiveness. The plan appeared to be succeeding when the rebels arrived in the Senate Building, as Kallus and his forces managed to corner Jarrus, Bridger, Hera Syndulla, and Trayvis. The rebels had arrived believing that Trayvis was in danger and that the Empire intended to capture him. Kallus identified Jarrus and Bridger, addressing the latter as "Jabba" in reference to their initial encounter, and encountered Syndulla for the first time. He demanded that they disclose the whereabouts of Orrelios and Wren or face execution by firing squad. The Imperials were caught off guard when Orrelios and Wren, who had entered the building from the roof, deployed smoke bombs between the rebels and Imperials, enabling the rebels to fight their way out and escape.
The rebels managed to evade capture and retreated into the sewers beneath the Senate Building, pursued by Kallus and his troopers. The rebels divided their forces, with Bridger and Syndulla escorting Trayvis while the others fled in a different direction. Trayvis revealed his true allegiance to Syndulla and Bridger, but they managed to knock him unconscious before reuniting with the other rebels. Kallus and his forces arrived as Jarrus employed the Force to halt a large fan that obstructed the rebels' path to freedom, and the ISB Agent ordered his forces to open fire on Jarrus. However, the Imperials were too late, as the rebels successfully escaped.

The Spectres' actions eventually garnered the attention of Grand Moff Wilhuff Tarkin, who visited Lothal. Agent Kallus, along with Minister Maketh Tua and the Inquisitor, formed part of the grand reception that welcomed Tarkin's shuttle at the Imperial headquarters. During the meeting, Tarkin rebuked Kallus for allowing the rebels to attack Imperial personnel, destroy Imperial property, and disrupt the Empire's trade. Kallus, ashamed to admit failure, responded that he had exhausted every resource to capture them but that the rebels had proven elusive. When Minister Tua mentioned that the rebel leader Kanan Jarrus was a Jedi, a skeptical Tarkin asserted that all the Jedi had perished during the Great Jedi Purge. Kallus believed that Tarkin's arrival would provide him with the necessary resources to apprehend the insurgents.
Following the Spectres' ambush of an Imperial supply convoy in the town of Jalath, Kallus was present at a meeting where Tarkin ordered the Inquisitor to execute the Imperial officers Commandant Aresko and Taskmaster Grint for their repeated failures to stop the Lothal rebel cell. Agent Kallus and Minister Tua were visibly horrified by the Grand Moff's actions, as their two men had been incompetent but loyal Imperials. Nevertheless, Kallus recognized it as a lesson that failure in the Empire would no longer be tolerated. Tarkin then instructed Agent Kallus to deploy probe droids throughout Lothal to locate the rebels. Disturbed by the execution of Aresko and Grint, Kallus vowed to avoid experiencing a similar fate.
Under Tarkin's directives, Agent Kallus and the Inquisitor devised a plan to trap the Spectres at the Imperial communications tower. Seeking to counter Imperial propaganda, the Spectres had hijacked the tower complex to broadcast a propaganda message to the neighboring systems. Following the rebel assault, Agent Kallus and the Inquisitor arrived with a force of three patrol transports and two Imperial Troop Transports, surrounding the complex and trapping the rebels. Kallus personally confronted Kanan outside the communications tower. When Kanan refused to surrender, the Inquisitor engaged the Jedi in a lightsaber duel. Following a brief confrontation, Kanan's rebel comrades managed to escape. Kallus succeeded in capturing Kanan at the expense of one patrol transport.
At dawn, Agent Kallus delivered the captured Jedi Kanan to Grand Moff Tarkin, who commended the Inquisitor for his work. Before Tarkin could interrogate Kanan, Kallus reported that the Spectres had gained control of the tower's transmitter. Kallus listened to Ezra's broadcast and expressed concern at Tarkin's orders to destroy the communications tower. Tarkin's destruction of the Lothal communications tower disrupted offworld communications on Lothal and the neighboring systems, forcing the local Imperial authorities to rely on courier droids. Kallus and Tarkin later oversaw the interrogation of Kanan, who, per standard Imperial procedure, was injected with a truth serum by an interrogator droid. Despite Kallus's best efforts, Kanan's Jedi training enabled him to resist the interrogation droid's mind probes. Displeased with Kallus' results, Tarkin ordered the Inquisitor to torture Kanan, who still refused to divulge any information on the rebellion. Frustrated by Kanan's resistance, the Imperials transferred the captive Jedi to the Mustafar system.
Agent Kallus remained on Lothal while Grand Moff Tarkin and the Inquisitor traveled to the Mustafar system with their Jedi captive. However, Kanan's rebel comrades launched a rescue mission for the Jedi. During that mission, the Inquisitor was killed, and the Grand Moff's Star Destroyer Sovereign and several TIE starfighters were destroyed by the rebels, who managed to flee into hyperspace with the assistance of the rebel network. Following the events in the Mustafar system, Agent Kallus was present at the Imperial headquarters' hangar bay when Grand Moff Tarkin arrived in a shuttle with the Emperor's Fist, Darth Vader. During the meeting, the operative expressed concern that the events on Mustafar would cause people to perceive the Empire as weak and vulnerable. Governor Tarkin disagreed and assured Agent Kallus that Lord Vader would crush the Spectres and their fledgling rebellion. Kallus was assigned to Vader's direct command as the Sith Lord and Tarkin initiated a siege campaign to punish Lothal and draw out the rebels.
As Vader's Lothal crackdown progressed, Kallus convened with Minister Tua to discuss her unsuccessful efforts to locate the Spectres. Under Tua's direction, the Imperial planetary authorities had augmented security and enforced a planetary curfew in accordance with Vader and Tarkin's demands to "squeeze" Lothal. However, Minister Tua doubted that such enhanced security measures would prove effective, correctly believing that the rebels had already departed from the planet. Frustrated, Kallus countered that Tarkin sought results due to the destruction of his Star Destroyer Sovereign. At that moment, Darth Vader interrupted their conversation and proposed that the Imperials lure the rebels back to Lothal and trap them there.

When the Minister expressed reservations about "punishing" the Lothalian population, the Emperor's Fist responded that she could raise her concerns with the Grand Moff himself, adding that Governor Tarkin had scheduled a meeting with her for the following day. When Minister Tua expressed fear that she would meet the same fate as Commandant Aresko and Taskmaster Grint, an unsympathetic Agent Kallus commented that he and Lord Vader would "manage in her absence." Fearing for her life and disturbed by the Empire's increasingly heavy-handed tactics, the frightened dignitary secretly contacted the Spectres and arranged to defect to the rebellion. However, Kallus suspected Tua's treason and dispatched a probe droid to monitor her movements.
The following day, Agent Kallus drove Minister Tua in a landspeeder to a disembarkation station where an Imperial shuttle awaited to transport her to Governor Tarkin. Kallus was escorted by several stormtroopers to deter any rebel attack. However, the Spectres launched an operation to rescue the dignitary. During the ensuing skirmish, Kallus battled against the Jedi Kanan, who had disguised himself as a Stormtrooper Commander. Tua ran to the shuttle but was killed in an explosion that had been deliberately orchestrated by Vader to discredit the rebels. Aware that his probe droid was observing the fray, Kallus feigned anger and accused the rebels of murdering Minister Tua. Despite his efforts, the rebels managed to escape, prompting Emperor's Fist to instruct the ISB Agent to lay siege to Lothal.
After the rebels stole a second Imperial shuttle and escaped Capital City, Kallus reported to Vader again and informed him that the rebels had not yet left Lothal. To draw the rebels out, the Dark Lord ordered the Agent to destroy Tarkintown, a refugee settlement that the rebels had assisted in the past. Kallus complied with Vader's orders and sent troops to raze the settlement and round up its inhabitants, who were imprisoned. Later, the rebels managed to escape Lothal with the assistance of the "galactic entrepreneur" Lando Calrissian's droid W1-LE, who helped them construct sensor buoys that confused the Imperial forces tracking them. However, Vader had allowed the rebels to escape to locate the Phoenix Cell, which operated a fleet in deep space. In the Emperor's Fist's subsequent attack run, the Spectres suffered significant losses and were forced to retreat. Upon the Sith Lord's return to their destroyer's bridge, Kallus congratulated Vader on his victory, only for the Sith Lord to demand that the bridge be cleared, forcing Kallus to leave so he could converse with the Emperor.

Following the Empire's triumph over the Phoenix Squadron and despite the rebels' ultimate escape, Kallus received a promotion of some sort and was tasked with assisting Admiral Kassius Konstantine in locating the rebels. While aboard the bridge of the Relentless, an officer informed him that Clone trooper Wolffe had reported an encounter with Jedi on the desert planet of Seelos. While Konstantine expressed skepticism given the clone's history of making delusional distress calls, Kallus insisted that all leads should be pursued and sent a probe droid to investigate.
Wolffe's intelligence proved accurate, and the probe droid successfully located Kanan and his rebel cell, who were perennial adversaries of Kallus. Upon arriving above Seelos, Commander Kallus and Admiral Konstantine issued an ultimatum to Wolffe, demanding that he and his fellow clones surrender the rebels or face "total and immediate destruction." Instead, Wolffe's associate, Captain Rex, challenged the agent and mocked the stormtroopers he commanded. Undeterred, Kallus initially dispatched a squadron of TIE fighters to the planet. After the rebels destroyed his TIE fighters, the ISB Commander personally led three AT-AT walkers against the clones' lone AT-TE walker.
Despite entering a sandstorm, Kallus ordered the assault to proceed. Unable to see or detect them, the Imperials were caught off-guard, and one walker was destroyed by a well-placed shot to the neck from Ezra Bridger. Kallus then ordered the remaining walkers to fire in the direction of the shot, chasing the ancient walker out of the sandstorm just as the rebel ship lifted off. Unaware that Admiral Konstantine had departed the Seelos system to rendezvous with an Inquisitor and was no longer able to provide air support, Kallus ordered his two remaining AT-AT walkers to continue the assault against the "obsolete" Clone troopers.
However, the clones refused to surrender, and their old walker, despite sustaining numerous hits, still had one good fight left in it. To the agent's disbelief, the clones brought their walker right up against Kallus' walker and rammed its legs to overbalance it. Rex then jumped onto the main cannon and openly challenged the walker's crew, deriding them as cowards. Thinking the clone suicidal, Kallus ordered his gunners to "finish him." Before they could do so, Kallus' AT-AT walker was attacked by the rebel ship Phantom and the second AT-AT walker, which had been hijacked by the rebels. Completing the rout, Rex fired a shot from the AT-TE's mass driver cannon directly into the neck of Kallus's own walker, crippling it. Kallus and his bridge crew managed to escape the ruined walker on a speeder, though one was left frantically running after it.

Following the events that transpired on Seelos, Kallus and Konstantine remained stationed on the Relentless alongside the Fifth Brother. On one particular occasion, a crew member detected an energy spike emanating from a deserted Republic medical facility. While Kallus and Konstantine were both doubtful of its significance, the Fifth Brother took a different view and chose to investigate personally. It was there that the Fifth Brother, accompanied by another Inquisitor known as the Seventh Sister, encountered the rebels Ezra, Sabine, Chopper, and Zeb, leading to a skirmish. Despite the combined efforts of the two Dark Side Adepts, the four rebels successfully escaped, managing to alert their fellow rebels to the presence of additional Inquisitors.
Later, Kallus oversaw a blockade around the planet Ibaar, suspecting, rightly, that the rebels would try to assist the exploited populace. His fleet successfully fought off an assault from Phoenix Squadron, destroying a CR90 corvette and even eliminating the Phoenix Leader in the process. The rebels then launched a counterattack using a prototype Bladewing starfighter, which broke through the blockade, allowing their supplies to reach the surface. The raw power displayed by the single fighter left Kallus in stunned disbelief.
Not long after the Ibaar incident, Swain, a female officer who had been mentored by Kallus, experienced a moment of realization. Coming to the conclusion that she could no longer be part of an organization that oppressed ordinary citizens, she chose to desert, along with her colleague Cogon, and they absconded with a Lambda-class T-4a shuttle. Kallus, however, managed to trace the shuttle's signal. Aboard the Relentless, he tracked his former protégée to the planet Thrad, from where she and her accomplice planned to travel to Klonoid, where they would join a local rebel cell. The Imperial agent pursued Swain and Cogon through the streets, eventually cornering him in an alley. Without his bo-rifle, Kallus appeared to be at Swain's mercy. However, two stormtroopers arrived just in time and shot Cogon in the back. The agent and his former protégée briefly exchanged blows, until Kallus was, once again, pinned to the ground, seemingly defenseless. But Kallus, to Swain's surprise, pulled a concealed weapon from beneath his armor and stunned her. He then contacted Admiral Konstantine, instructing him to destroy a suspicious vessel attempting to depart the planet—the very ship Swain and Cogon were intending to board. Finally, the agent had Swain taken aboard Admiral Konstantine's Star Destroyer for interrogation, and reported his success to Lord Vader.
Kallus later received a communication from Admiral Brom Titus, who boasted about capturing the rebels Jun Sato and Ezra Bridger. Kallus pledged to meet Titus' prototype Imperial Interdictor and advised him to keep Bridger under heavy guard, but Titus disregarded his warnings. Upon Kallus' arrival, he discovered the Interdictor destroyed, the rebels having escaped, and a humiliated Titus adrift in an escape pod, much to Kallus' secret amusement.
After the Inquisitor known as the Seventh Sister detected a rebel presence on the planet Garel, Agent Kallus instructed Admiral Konstantine to redeploy the Imperial fleet from Lothal to Garel. He persuaded the Seventh Sister and the Fifth Brother to collaborate in capturing Phoenix Squadron, which included the Spectres, his long-standing adversaries. Kallus also led the ground assault and attempted to capture the Spectres. However, Ezra Bridger used the Force to hurl Kallus against a wall, rendering him unconscious. After the Spectres made their escape, Kallus contacted Admiral Konstantine for information on the rebel fleet's location. Konstantine reported that he had no information, as the rebels had already jumped into hyperspace.
Agent Kallus and Admiral Konstantine later commanded an Arquitens-class command cruiser in an attempt to capture the Ghost above the planet Nixus. Prior to this, the crew of the Ghost had rescued two Lasat refugees named Gron and Chava the Wise, who were searching for the mythical Lasat homeworld of Lira San. Despite their best efforts, the Ghost managed to jump to hyperspace before the Imperials could ensnare it. However, the Imperials had succeeded in capturing the Weequay pirate Hondo Ohnaka, who had initially informed the crew of the Ghost about the Lasat refugees. Ohnnaka was compelled to work for the Imperials and was able to locate the Ghost due to a tracker implanted in his communications device.
Kallus' Imperial light cruiser tracked the Ghost to an imploded star cluster situated in Wild Space. Upon exiting hyperspace, Kallus gave the rebels one minute to surrender before he destroyed their starship. Realizing that Kallus was the prophesied "warrior" from Lasat legend, Zeb used his bo-rifle to guide the Ghost through the treacherous star cluster. When the rebels ignored his ultimatum, Kallus dispatched two TIE fighters after the Ghost, but they were torn apart by the gravitational forces of the star cluster. Kallus' light cruiser then opened fire on the Ghost but each shot missed. Kallus was compelled to withdraw his cruiser after it began to sustain damage from the gravity field. While Kallus hoped that the Ghost would be destroyed, he was disappointed when the rebel freighter managed to enter the star cluster safely.

Kallus' subsequent action involved setting a trap for the crew of the Ghost at an Imperial construction module orbiting the desert planet of Geonosis. Although he successfully lured the rebels into the trap, his forces failed to capture them, and the rebels managed to escape into space. During the conflict, Kallus engaged the Lasat in hand-to-hand combat. When Zeb attempted to escape in an escape pod, Kallus pursued him into the pod and attempted to subdue him. The escape attempt resulted in Kallus breaking his leg and the pod crash-landing on the frozen Geonosian moon of Bahryn.
Zeb spared Kallus' life, unwilling to defeat his adversary in an unfair fight. The two enemies were forced to work together to avoid freezing to death and being killed by the bonzami, fierce predators that inhabited the moon. When the creatures attacked and Kallus recovered his weapon, he passed up the opportunity to kill Zeb and instead helped him fend off the predators. After saving each other's lives, the two adversaries opened up to one another and formed an unexpected bond. After their heat source failed, Zeb located a small meteorite still glowing and emitting heat, which he gave to Kallus. When the bonzami attacked them again, they managed to escape the underground cavern to the surface following a struggle. Here Kallus had the opportunity to shoot Zeb but opted to save him from the bonzami instead.
The following morning, the crew of the Ghost returned for Zeb, after picking up his transponder. Zeb invited Kallus to come along, assuring him that he would be treated fairly. However, Kallus declined and chose to wait for the Imperials. After the rebels had departed, Kallus was rescued by a passing independent trader, as the Empire had exhausted its allocated time and resources for finding him. After finally returning to the Imperial fleet, Kallus encountered Admiral Konstantine, who barely acknowledged him, much to Kallus' dismay after witnessing the camaraderie Zeb had shown him. After limping back to his quarters, he placed the meteorite Zeb had given him on a shelf before reflecting on his sobering experience with his enemy, now privately questioning the Empire.

Following his encounter with Zeb, Kallus' doubts began to intensify. They ultimately drove him to defect to the rebellion. He operated as a spy under the alias Fulcrum, providing secret information to the rebellion through broadcasted messages.
In 2 BBY, Kallus was, ostensibly, still hunting the rebels alongside Governor Pryce, Admiral Konstantine, and Grand Moff Tarkin. Pryce then revealed that Grand Admiral Thrawn and his Seventh Fleet would be spearheading their efforts against the rebels. Upon learning that Thrawn had recently been promoted for his actions in the Battle of Batonn, Kallus remarked that the civilian casualties exceeded the insurgent casualties. In response, Governor Pryce informed him that there were no longer any rebels in the Batonn sector. Later, Kallus accompanied Pryce and Konstantine to Yarma, where the Phoenix rebels had raided the Imperial floating junkyard Reklam Station. Kallus was present when Thrawn ordered Pryce and Konstantine to allow the rebels to escape with their "meager reward" of five stolen Y-wing starfighters.
Subsequently, Kallus informed the rebels that there were cadets at the Imperial Skystrike Academy who wished to defect to the rebellion. He then accompanied Governor Pryce to the Skystrike Academy. Pryce had arrived after hearing rumors of several cadets attempting to defect and had Captain Vult Skerris conduct a combat simulator in space to draw out the defectors. Her plan was successful, and the Imperials killed one of the defectors and captured the other three. In an interrogation room, Kallus recognized Sabine, and when she revealed her identity to save the other two cadets, Pryce instructed Kallus to take the other two cadets, Hobbie and Wedge, to another cell. Sabine commented to Kallus "looks like they have found someone who can do your job," before Kallus took the two cadets into their cell.
When Sabine broke free from Pryce's grasp and fled with Hobbie and Wedge, the Imperials trapped them with blast doors. Kallus suddenly appeared and opened one of the doors, advising them on how to escape. He then told Sabine to send his regards to Garazeb Orrelios, and that they "we're even now." Kallus then closed the blast door after the three left and hid himself until the alarm was off.

Later, Agent Kallus accompanied Governor Pryce aboard the bridge of a Star Destroyer. Kallus complimented the Governor for her plan to lure the Spectres into a trap at a fuel depot. However, Pryce responded that her plan would only succeed if she captured the rebels. Kallus was present when Pryce dispatched Imperial forces to investigate a distress signal originating from Agamar.
Following his encounter with Sabine at the Skystrike Academy, Kallus learned that the Empire was developing a new weapon at the Imperial Armory Complex, he then contacted the Phoenix Squadron, who were planning to attack the factory. Due to the high rate of malfunctioning vehicles produced by the Lothal Imperial factory, the Imperial High Command dispatched Grand Admiral Thrawn to restore order and to investigate the factory for saboteurs. Indeed, a rebel cell led by former Governor Ryder Azadi had been sabotaging the vehicles.
With Governor Pryce and Lieutenant Yogar Lyste, Agent Kallus summoned the factory workers for an assembly. Thrawn then gave a speech berating the workers for their shoddy craftsmanship. He then forced the former farmer Morad Sumar, a member of Azadi's cell, to demonstrate a 614-AvA speeder bike. Due to a faulty engine, the bike exploded during the test demonstration, killing Sumar. Kallus was horrified by Thrawn's action but Governor Pryce smirked. Thrawn then ordered his Imperial subordinates to lock down the factory and to question the workers. However, the rebel infiltrators Ezra, Kanan, and Chopper managed to escape the screening and headed to Section A2.
While Thrawn and Governor Pryce discussed the secrets hidden inside the factory's Section A2, Kallus asked his superiors for more information on the project so that he could question the workers more effectively. Pryce responded that all that Kallus needed to know was that the Grand Admiral had a new fighter initiative. When Kallus expressed skepticism about the prospects of one fighter changing the war, Thrawn replied that victory and defeat were determined by the smallest details. Kallus was present when Thrawn ordered another worker to demonstrate an AT-DP walker. At Thrawn's command, Kallus released the walker from its station. When the walker collapsed, Thrawn gestured for his men to arrest the worker.
Later, Kallus and Lieutenant Lyste visited Thrawn's Office, which contained several objects relating to the Spectres. When Thrawn asked the two officers about one of Sabine's graffiti art pieces, Lyste remarked that it was merely a section of a retaining wall. By contrast, the more perceptive Kallus recognized the drawing as a starbird, a creature of light that had been adopted as a symbol of the Phoenix Squadron. Kallus interpreted the starbird as a symbol of the rebel's commitment to victory. Thrawn agreed and theorized that the Spectres had a special connection to Lothal.

When Thrawn asks if they had found any more subversives, Lyste informed the Admiral that two workers had disappeared following Thrawn's speech but that they had left behind their uniforms. Kallus suggested issuing an alert but Thrawn advised against it since he believed that the rebels were already inside the factory and had found new disguises. When Kallus asked Thrawn whether he thought that the rebels were more than saboteurs, the Admiral responded that the rebels were after the contents of Section A2 and sent Kallus and Lyste to secure it.
Spotting Ezra and Kanan in their stormtrooper disguises with their droid, Kallus ushered them into a turbolift under the pretext of ordering them to secure a perimeter. Inside the lift, Kallus introduced himself to the rebels, who fought him. However, Kallus managed to convince them that he was a friend by identifying himself as Fulcrum and quoting the code phrase "by the light of Lothal's moons." Kallus also reminded the two that he had befriended Zeb on Bahryn and helped Sabine to escape. While Chopper believed Kallus, Ezra and Kanan were slower to trust their former adversary.
Nevertheless, Kanan convinced Kallus to help them send a signal to his local contact Ryder Azadi. Kallus led the rebels into a communications station and pretended to fight them. The rebels managed to use their blasters and lightsabers to stun the stormtroopers and officer at the station. Kallus then allowed Chopper to upload Kanan's comlink from the station's port. After the rebels had contacted Ryder, Kallus told them to head to the east gate where they would find an AT-DP walker in the hangar. To make it appear that Kallus had put up a fight, Ezra hurled the ISB agent against the glass monitor. While hurt by the shattered glass, Kallus was pleased that he had helped his new allies escape.
Due to Kallus' help, Ezra, Kanan, and Chopper managed to escape the factory on the AT-DP walker and link up with Ryder's cell. They also managed to send the stolen plans to the Phoenix Squadron, which discovered that Thrawn was developing a new starfighter. Ezra and Kanan credited Kallus with helping them escape the factory. While Hera and Sabine believed that Kallus could not be trusted yet, Zeb vouched for his former adversary and remarked that he must have accidentally recruited him.
Later, Thrawn questioned Kallus about his encounter with the rebels. Having analysed the rebels' escape pattern, Thrawn suspected that the rebels had inside help from a mole. Instead of questioning Imperial personnel, Thrawn decided to set a trap for the mole. Feigning loyalty to the Empire, Kallus commended Thrawn for his "flawless" strategy.

Agent Kallus was later privy to Grand Admiral Thrawn's plan to dispatch E-XD-series infiltrator droids across the Outer Rim Territories to search for rebel bases. While stationed aboard a Star Destroyer, Kallus was informed by another officer that they had lost contact with EXD-9. Unable to track down the droid's location, the officer suggested alerting Imperial High Command. Kallus advised him not to under the pretext that chasing down every comm failure would be a waste of time. Instead, he advised the officer to wait until the next cycle.
Using his Fulcrum pseudonym, Kallus sent a recorded transmission to Chopper Base warning the rebels that the Empire was dispatching E-XD infiltrator droids across the galaxy. He also added that the Empire had lost contact with one and would come searching for it soon. Fulcrum's warning alerted Kallus' rebel friend Zeb, who realized that the "stray" protocol droid he found was an infiltrator droid. Working with Chopper and the RA-7 protocol droid AP-5, Zeb overpowered the infiltrator droid. The three rebels then reprogrammed EXD-9 into an improvised bomb which they used to destroy a Star Destroyer.
Kallus was on the bridge of another Star Destroyer when he witnessed the other ship go up in flames. Feigning shock and anger, he asked what happened. An officer informed him that one of their infiltrator droid's proton warheads had gone off prematurely. Kallus secretly smiled and later sent a transmission to Chopper Base praising the rebels for their ingenious plan to neutralize the infiltrator droid. Later, he visited Thrawn and reported that the rebels had reprogrammed an infiltrator droid into an improvised bomb. Both men regarded the rebel plan as ingenious. When Kallus noticed that Thrawn was in good spirits despite the setback, the Grand Admiral replied that he had narrowed down his search from thousands of systems to the 94 systems to which he had sent infiltrator droids.

Sometime later, Kallus was awakened from his sleep when Lieutenant Lyste brought the ship into battle-station mode to intercept a stolen shuttle. Upon entering the light cruiser's bridge, Kallus was briefed by Lyste about the shuttle heist. After Lyste's light cruiser trapped the stolen shuttle with its tractor beam projector, Kallus headed to the landing bay to interrogate the shuttle thief, who turned out to be the rebel Ezra Bridger. Bridger was disguised as a bounty hunter and accompanied by Chopper and AP-5, who claimed to be unwilling passengers aboard the stolen shuttle.
Kallus met with Ezra in the light cruiser's detention cell and scolded him for getting captured. Ezra informed him that the Empire was monitoring his most recent Fulcrum Transmission and that he came to get him out before he got exposed and executed for treason. Before they could make their next move, Lieutenant Lyste entered the brig to inform Kallus that Grand Admiral Thrawn had summoned both of them for a meeting aboard his Imperial Star Destroyer Chimaera. To protect Ezra, Kallus claimed that the prisoner was a bounty hunter from Lothal. Seeking to curry favor with Thrawn and redeem his image after the incident with Princess Leia Organa, Lyste arranged for Ezra to be brought aboard Thrawn's ship. Kallus and Lyste then traveled to the Chimaera aboard the Sentinel-class landing craft Shuttle TYA77.
Once aboard the Chimaera, Kallus and Lyste headed to Thrawn's Office. Meanwhile, the droids searched for a port to download a new set of clearance codes for the rescue team members Kanan and Rex. Ezra was thrown into the Chimaera's detention block. At Thrawn's Office, Kallus and Lyste were met by Thrawn, Konstantine, and Kallus' former ISB instructor and the Head of the Imperial Security Bureau, Colonel Wullf Yularen. During the meeting, Kallus learned about Thrawn's investigation into Fulcrum and how he was close to discovering the Phoenix Squadron's base on the planet Atollon. Following the meeting, Kallus spent time with his former instructor and took the opportunity to sow disinformation.
Knowing that Thrawn was close to uncovering his identity and feeling he could do more good for the Rebel Network by remaining undercover, Kallus decided to implicate Lyste as Fulcrum. Taking advantage of Lyste's woeful inexperience and naivete, he tricked Lyste into believing that Governor Pryce was Fulcrum and told him to spy on her. Kallus also stole Lyste's code cylinder. After finding AP-5 and Chopper, Kallus freed Ezra from his cell and told him about Thrawn's search for the rebel base. Kallus tried to convince Ezra to give him the location of the rebel base so that he could delete it from Thrawn's database. Not fully trusting Kallus, Ezra insisted that Kallus wait until they had extracted him from the Chimaera. AP-5 then managed to convince Ezra to support Kallus' plan by pointing out that he could get a new set of clearance code's from Thrawn's office.
After tricking Lyste into tailing Pryce, Kallus obtained an Imperial uniform for Ezra. The two then infiltrated Thrawn's office with Ezra using a Jedi mind trick to convince the stormtrooper sentry that he was Lieutenant Lyste. Once inside, Kallus instructed Chopper to delete Atollon and to add another planet. Before they could leave, Thrawn returned to his office. Kallus and his rebel allies managed to hide in the dark corners of the office. To distract Thrawn, Kallus then reprogrammed the Grand Admiral's DT-series sentry droids to attack Thrawn, thus implicating Lyste.
Kallus and his rebel companions then headed back to the Chimaera's hangar bay to rendezvous with Kanan and Rex's shuttle. However, Thrawn had learned about the rebel infiltrators and had sent Governor Pryce and Colonel Yularen with stormtroopers to deal with the second set of intruders. Believing that Pryce was Fulcrum, Lieutenant Lyste stunned her. Kallus then tackled Lyste and knocked him to the ground. At that point, Kallus changed his mind and told his rebel friends he would stay behind in order to continue supplying them with intelligence, as Lyste had made himself look like he was Fulcrum by stunning the governor. When Yularen finally arrived, Kallus publicly accused Lyste of being Fulcrum, which Kallus knew would likely result in the Imperial officer being executed after his arrest.
Lyste tried to protest his innocence but Kallus remained impassive. Later, Kallus attended a meeting with Pryce, Yularen, and Thrawn. Yularen claimed that Lyste's cylinder code implicated him as Fulcrum. Pryce bought Kallus' explanation while the ISB agent apologized to Thrawn for failing to stop Lyste's purported assassination attempt. Thrawn publicly praised Kallus for his services and dismissed him and Pryce. In private however, Thrawn informed Yularen that Kallus was the real Fulcrum. Instead of arresting him, Thrawn decided to use Kallus to lead them to the rebel base.

Sometime after Lyste's capture, Kallus utilized a reconfigured mouse droid to secretly listen to a discussion involving Grand Admiral Thrawn, Grand Moff Tarkin, Governor Pryce, and Admiral Konstantine. While secretly listening to their discussion, Kallus discovered that Thrawn knew about the planned assault by Phoenix Squadron and General Jan Dodonna's Massassi Group on the TIE Defender factories located on Lothal. Kallus then went back to Ezra's previous residence and tried to alert the rebels that Thrawn had knowledge of their strategy. However, he realized that his transmitter's signal was being blocked, and Kallus could only send a partial message.
The phrase "by the light of Lothal's moons" startled Kallus, who then found Thrawn standing behind him; Thrawn had known Kallus was the mole ever since Lyste was arrested. Kallus attempted to engage Thrawn in combat, but he was easily defeated and captured by Thrawn's Death troopers. Thrawn then used the flight paths of General Dodonna's fleet, along with Kallus' Fulcrum signals, to pinpoint the location of Chopper Base on the planet Atollon. When Kallus insisted that no planet existed at that location, Thrawn belittled Kallus for his supposed lack of artistic appreciation. Thrawn clarified that although the Atollon system was absent from Imperial charts, it was represented in the art of the ancient inhabitants of the sector.
Subsequently, Kallus was taken to the bridge of the Chimaera and compelled to witness the battle as a prisoner, in the presence of Thrawn and Governor Pryce. After Thrawn instructed Admiral Konstantine to maintain his Interdictor ship in formation with the fleet, Kallus derided Thrawn for seeking personal glory. However, the Grand Admiral countered by saying that his sole focus was achieving results for his Emperor. Later, Kallus and his captors watched as Commander Jun Sato's command ship, the Phoenix Nest, collided with Konstantine's interdictor cruiser, resulting in the destruction of both vessels. This occurred because Konstantine had disobeyed Thrawn's orders to remain in the center of the formation and instead attempted to gain personal glory by intercepting Commander Sato's ship.
Before Thrawn departed for the ground assault, Kallus sarcastically warned him that he had previously been in Thrawn's position and had been defeated by the rebels. However, the Grand Admiral responded that he was different. Thrawn's forces successfully stormed Chopper Base, but the Grand Admiral was denied total victory when a mysterious Force entity known as Bendu attacked and devastated the base, thus providing the rebels with an opportunity to escape. Kallus remained aboard the bridge of the Chimaera when Ezra and Sabine's Clan Wren reinforcements launched a rear assault on the Seventh Fleet's last remaining interdictor cruiser.
After the rebels succeeded in destroying the last interdictor cruiser, Kallus smirked and remarked to Pryce that she had "made a mess of Thrawn's fleet." Enraged, Pryce ordered two stormtroopers to eject him from the ship through an airlock. Thanks to his ISB combat training, Kallus easily subdued his captors, made his way to an escape pod, and ejected from the Star Destroyer. Following contact with Hera, he was rescued by the Ghost. Once aboard, Kallus expressed his gratitude to Jarrus for accepting him, and Jarrus in turn thanked him for risking everything for the Rebellion.
Later, Kallus formally became a member of the Rebel Alliance and served as a captain within the Alliance Army. Kallus served in the Alliance's Massassi Group, collaborating with the Spectres. After Hera's squadron of Y-wings returned to Yavin 4 following a mission, Kallus interrupted the Spectres' reunion to inform them that the rebel leader Mon Mothma had requested to meet with them. During the meeting, the rebels discussed information about the Empire's new relay station on Jalindi, information that had been provided by the Partisans' leader, Saw Gerrera. Kallus voiced his disapproval of Saw's methods for obtaining information but ultimately convinced the Alliance leadership to authorize a mission to plant a spike on the Jalindi relay.
Subsequently, Kallus and Rex operated the VCX-100 light freighter Ghost while the Spectres undertook a mission to Lothal to steal a TIE/D Defender. The rebels' strategy involved rendezvousing with the smuggler Cikatro Vizago's ship, the Broken Horn, to infiltrate Lothal. Kallus cautioned that Vizago was untrustworthy, but Ezra disagreed. Before the Spectres departed, Hera placed Rex in command of the Ghost. Kallus initially believed that Hera was referring to him and pointed out that he had previously commanded Star Destroyers. Rex corrected him, and the former Imperial vacated the pilot's seat for Rex.

Following the Spectres' mission to the Lothal Jedi Temple, Kallus accompanied Hera and Rex aboard the Ghost to the planet Seelos, which was the location of Rex's fellow Clone veterans Gregor and Wolffe's home at Joopa Base. At Gregor and Wolffe's modified AT-AT walker known as "Joopa Base," the rebels also encountered the Weequay pirate Hondo Ohnaka, his Ugnaught companion Melch, and the Mandalorian bounty hunter Ketsu Onyo, who were former friends of Ezra. After briefing them, these allies agreed to assist Ezra in liberating his homeworld of Lothal.
While traveling back to Lothal, the rebels and their allies waited aboard the Ghost in hyperspace to latch onto an Imperial container transport at Hondo's suggestion. Although Kallus and Rex were skeptical, Hondo's plan proved successful, and the rebels were able to infiltrate Lothal by attaching themselves to a container transport. Upon landing, Kallus, along with Rex, Gregor, and Wolffe, aided Ezra and Ryder's forces in defeating Governor Pryce's forces at the Lothal cliff dwelling. The rebels also managed to capture Pryce, who was essential to Ezra's liberation strategy.
Before the assault on the Dome, the center of Imperial power on Lothal, Kallus and Ryder escorted the captive Pryce. When Pryce denounced Kallus as a traitor, he retorted that the day he betrayed the Empire was the day he stopped betraying himself. With the assistance of the White Loth-wolf, Ezra successfully coerced Pryce into helping them gain access to the Dome.

The rebels then journeyed to the Dome in two patrol transports. For the mission, Kallus disguised himself as an Imperial Navy Trooper and kept a close watch on Pryce, who complied with all of the rebels' instructions, and would know if Pryce gave them the wrong codes. Thanks to Pryce's cooperation, the rebels managed to fight their way into the Dome and seize the command center. Working alongside Ezra and Ryder, Kallus assisted in issuing a false Protocol 13 to order the recall of the entire Imperial garrison on Lothal to the Dome.
Although their plan was successful, they were unable to launch the Dome into space due to the return of Grand Admiral Thrawn aboard the Chimaera. Thrawn had his assassin, Rukh, disable the power terminals that powered the Dome's deflector shield generator, which allowed him to bombard Capital City. After Ezra departed to confront Thrawn, Kallus participated in a two-pronged assault to reactivate the generators. He, Zeb, and Gregor were part of Team B, which was assigned the task of reactivating the southern power terminal.
Despite facing strong resistance, Kallus and his team managed to reach the southern power terminal. There, they were attacked by Rukh and several Death troopers. While Zeb engaged Rukh in combat, Kallus and Gregor confronted the Death troopers. During the struggle, Gregor was shot in the chest and mortally wounded. Kallus tended to the fallen Clone trooper, who urged him to restore the shields. Following Zeb's instruction, Kallus activated the power terminal, and the resulting surge killed the trapped Rukh.
After this Ezra had the young rebel Mart Mattin summon a pod of purrgil. The purrgil destroyed the Imperial blockade and attached to the Chimaera, causing the ship, Thrawn, its crew, and Ezra to vanish into hyperspace. With Thrawn's elimination, the rebels completed their objective of launching and destroying the Imperial dome. Kallus escaped with his fellow rebels aboard the Ghost before the "Dome" exploded.
As the Ghost flew over the cheering crowds, Kallus observed that the people of Lothal were now fully aligned with the rebellion. General Syndulla responded that if the Empire desired a fight, the rebels would be prepared. Despite the rebels' concerns, the Empire never returned to Lothal.
Following the Liberation of Lothal, Kallus continued to operate under the Fulcrum identity. On one mission for the Alliance, he was tasked with contacting the grand-engineer known as Lony Coleema. Along with his companion droid Dee-Four, the two met Coleema on the asteroid outpost Z-LOQ. After a brief exchange, Coleema successfully transferred important information into the droid. Before departing, Kallus provided her with a subspace transponder in case she needed to request assistance from the Alliance. Shortly afterward, Coleema was kidnapped by the bounty hunter IG-88 and transported to a planet. Coleema encountered and activated a droid named Are Zero Are Zero "Roro" who proceeded to activate the transponder which alerted Kallus to her situation. Using the ship Glimmer of Hope, he and Dee-Four rescued Coleema and Roro from the planet. Coleema subsequently awoke on the ship and after being briefed by Kallus, professed a desire to go home.
After the [Galactic Civil War](/article/galactic_civil_war], Zeb brought Kallus to the planet Lira San, revealing to the former ISB agent that the Lasat species had not only survived the Empire's wrath but were thriving. The Lasat people, having forgiven Kallus, welcomed him as one of their own. Kallus retired to Lira San.
Kallus would later author a memoir, in which he reflected on his role in the war, from Imperial agent to Rebel defector, titled Honor Lost on Lasan: Serving the Empire, Fighting for the Alliance. In it he described his realization of the evils of the Empire. Some planets would incorporate his text into their education programs to teach future generations about the war. Historian Beaumont Kin, after the Battle of Exegol, would reference the impact of Kallus' memoirs in his own history book The Rise and Fall of the Galactic Empire.

As an Agent within the Imperial Security Bureau, he was a dedicated supporter of the Empire, and his loyalty was unwavering. Kallus also appeared to have a degree of personal loyalty toward Darth Vader, the Emperor's Fist, executing his directives with a zeal that he did not display when subordinate to other leaders. He also seemed slightly displeased when he was excluded from his superior's discussions with the Emperor. Kallus despised chaos and rebellious activities, dedicating his life to ensuring stability within the Empire. He possessed a sense of superiority over others, which amplified his disdain for lawlessness in the Outer Rim Territories. Through his position as an ISB Agent, Kallus aspired to achieve greater prominence within the Empire. Every time he managed to defeat rebel insurgents, he viewed it as a victory for the Empire, a victory that could potentially lead to greater opportunities. Nevertheless, he had declined several promotion offers to remain on the front lines with the Imperial Security Bureau and once stated that his duty was to serve the Empire, not his own ambitions.
As a skilled fighter, Kallus did not command soldiers from a distance but instead fought alongside them on the front lines, including against the crew of the Ghost. Kallus demonstrated a willingness to fight Orrelios on Lothal in bo-rifle combat and appeared to take pride in his role in the destruction of the Lasat species, although his actual involvement in it would later be revealed to be less significant than he claimed. Kallus believed that his actions were necessary to fulfill his duties and ensure stability and efficiency within the Empire. While he valued honor, Kallus demonstrated his ruthlessness by once kicking one of his men into a chasm, resulting in his death, simply for asking an innocent question. When serving under Vader's direct command, Kallus exhibited a disturbing enthusiasm in carrying out his superior's instructions, such as assisting in luring Maketh Tua to her death.

Beneath his outward display of confidence, Kallus was not as cold and cruel as he appeared. He was genuinely disturbed by the sudden and brutal execution of Cumberlayne Aresko and Myles Grint on the orders of Governor Tarkin, whom he had considered loyal fellow Imperials. Despite being a hardened soldier who rarely showed any vulnerability, he revealed a more sensitive side when he was forced to cooperate with Zeb to survive, exposing his tough exterior as merely a facade to conceal his feelings of sadness, confusion, and being lost, haunted by his past. His conversations with Zeb revealed that he held a somewhat idealized view of the Empire, genuinely believing that Zeb would receive a fair trial if he surrendered and cooperated. Kallus also repaid his debt to Zeb by allowing his friend Sabine Wren and two defecting pilots to escape.
Kallus also appeared to deliberately ignore at least some of the Empire's atrocities, stating that he "never asked questions" regarding the missing population of Geonosis and arguing against the idea that the Empire was responsible. He revealed that he kept his bo-rifle not as a trophy but out of respect for the Lasat he had defeated, who presented him with the weapon as a gift for defeating him, in accordance with Lasat tradition. He developed a respect for Zeb and apologized for his role in the Imperial pacification of Lasan, claiming that he had not intended it to be a massacre. In light of the unique bond he formed with his enemy, he was saddened by the cold and indifferent reception he received from his own comrades upon his return. His loyalty was further tested when one of Grand Admiral Thrawn's campaigns resulted in a high number of civilian casualties, and he expressed his concerns to the Grand Admiral.
Kallus' growing disillusionment with the Empire and his friendship with Zeb eventually led him to secretly assist Sabine in her operation to extract defecting Imperial cadets Wedge and Hobbie from the Skystrike academy. He provided Sabine Wren and the cadets with information on which levels to avoid and told Wren that he and Zeb were now even. Kallus' advice proved to be genuine, and Sabine and the cadets were able to escape. Similar to Minister Maketh Tua, Kallus' increasing dissatisfaction with the Empire's brutal methods led him to begin assisting the rebels. Kallus' sympathy for the rebellion motivated him to leak information about Thrawn's secret TIE fighter program to the Phoenix Squadron. He also aided Bridger and Jarrus in escaping from the Lothal Imperial factory. Kallus was visibly horrified by Thrawn's ruthless efforts to identify saboteurs at the factory, particularly the simulation "accident" that resulted in the death of the worker Morad Sumar.

Kallus' pro-rebel sentiments led him to leak information about Grand Admiral Thrawn's E-XD infiltrator droids to the rebellion. This information enabled the rebels Zeb, Chopper, and AP-5 to neutralize the threat. Kallus was impressed to learn that the rebels reprogrammed the infiltrator droid into an improvised bomb, which destroyed an Imperial Star Destroyer.
Kallus's interactions with the rebellion led him to trust Ezra, Chopper, and AP-5 when they arrived to rescue him from Thrawn's crackdown. Kallus also manipulated Lieutenant Lyste's trust to trick him into spying on Governor Pryce and framing him as Fulcrum. Kallus' newfound sympathy for the rebellion made him willing to harm his fellow Imperial comrades in order to advance the rebels' interests and protect his identity as Fulcrum. Kallus also maintained a respectful relationship with his former ISB instructor, Colonel Wullf Yularen. Kallus took advantage of Yularen's respect for him to mislead the Colonel into believing that Lyste was Fulcrum. However, Thrawn deduced that Kallus was the real Fulcrum after learning that Kallus had withheld information about the identity of the rebel operative Ezra Bridger.
Kallus' newfound loyalty to the rebels prompted him to attempt to warn them that Thrawn had learned about their planned attack on Lothal. After Kallus engaged in a fierce but ultimately futile fight against Thrawn, the Grand Admiral remarked that he had the heart of a rebel, which Kallus took as a compliment. During the Battle of Atollon, Kallus watched the attack on the Rebel base with anger and despair, but he seized any opportunity to taunt his former Imperial comrades. Governor Pryce grew impatient with Kallus' taunts and ordered her stormtroopers to throw him out of the airlock. However, Kallus was then able to overpower his guards and escape in an escape pod to join the rebels. When Kallus expressed gratitude to his former rebel foes for taking him in, Jarrus praised him for risking everything to help the rebellion.
As a rebel, Kallus shared Mon Mothma's aversion to the Partisan leader Saw Gerrara's brutal methods. Kallus also believed that the smuggler Cikatro Vizago was untrustworthy and cautioned his rebel comrades against trusting Vizago.
Kallus fought alongside Ezra and his former rebel foes during the Liberation of Lothal. When confronted by Governor Pryce about his defection, Kallus responded that he stopped betraying himself the day he betrayed her Empire. Having befriended Zeb, Kallus traveled with Zeb following the Galactic Civil War to Lira San, where he reconciled with the Lasat people he had formerly persecuted.

Kallus received training in both riot control and heavy combat, and he wore an ISB helmet designed for such situations. He underwent extensive training to become proficient in fighting and was a formidable opponent in hand-to-hand combat. During the fall of Lasan, Kallus defeated a Lasat guardsman, who presented Kallus with a bo-rifle as a sign of his defeat. He successfully modified this weapon for close-quarters combat and was able to go toe-to-toe with Orrelios, a trained Honor Guardsman, during a fight on Lothal. While Kallus received training in unarmed combat during his time at the Imperial Academy, he was outmatched by Grand Admiral Thrawn in combat. Later, Kallus used his close-quarters combat skills to overpower two stormtroopers and escape the Chimaera aboard an escape pod.
As a high-ranking Imperial officer and ISB operative, Kallus possessed extensive knowledge of code cylinders and the inner workings of Imperial institutions. He utilized his inside knowledge of the Imperial Military to leak vital intelligence to the rebellion and attempted to deceive Thrawn. He was also highly skilled in robotics and programming, as demonstrated by his reprogramming and redesign of an MSE-series-6 ("mouse") droid for surveillance and his reprogramming of Grand Admiral Thrawn's own assassin droids.
After defecting to the Rebellion, Kallus effectively utilized his combat skills, fighting alongside his rebel comrades. He also used his knowledge of Imperial protocol and procedure to infiltrate the Dome and initiate Protocol 13.

Agent Kallus wore a gray Imperial uniform with a pair of black boots, gauntlet gloves over his hands, and a fleximetal cuirass. The armor was quite durable, being able to sustain a ricochet shot from an E-11 medium blaster rifle. His distinctive ISB combat helmet had blast-proof cheek pieces. His belt was fitted with an identity disk. The metallic rank insignia on the left breast of his armor comprised one row of four tiles, two blue, one silver, and one red. Later, his rank insignia changed, consisting of five tiles, three blue, and two yellow. During his time as a Commander, Kallus owned at least one red-tipped code cylinder. Kallus also carried a RK-3 blaster.
In battle, Kallus wielded a J-19 bo-rifle, a gift from a member of the Lasan High Honor Guard whom he had defeated. He was proficient with this weapon in both ranged and close combat. As a Fulcrum operative, Kallus was skilled in operating a transmitter, which he kept in Ezra's former home. After joining the Rebel Alliance, Kallus wore an earth-colored Alliance uniform, displaying the rank of Captain.

Agent Kallus serves as one of the main adversaries in the animated television series Star Wars Rebels, with British actor David Oyelowo providing his voice. Kallus was conceived as a rebel hunter and the most frequent antagonist for the rebel crew, someone who would be actively involved in the conflicts between the rebels and the Empire. Kallus underwent several design iterations, including one where he was depicted as a Chiss, a species that originated in the Star Wars Legends novel Heir to the Empire by Timothy Zahn. The production team ultimately decided on a human character, and Oyelowo was chosen to play the role. Carrie Beck, the show's co-creator, stated that Oyelowo was able to provide "a voice that is very authoritative, and very commanding, and very cool without betraying any sense of insecurity or weakness."
The character was initially revealed at the 2014 Hasbro Toy Fair. He was featured in various trailers, including the full trailer released on May 4, 2014, before becoming the subject of his own introductory video. His first on-screen appearance was in Star Wars Rebels: Spark of Rebellion, the show's premiere television movie that debuted on October 3, 2014. Several chapters in the chapter book Battle to the End, which was written as a supplement to Star Wars Rebels, are presented from Kallus' perspective.

Initially known only as Kallus, the first name of Alexsandr was revealed by Dave Filoni, the creator of Star Wars Rebels, during a July 2017 podcast interview with The Wookiee Gunner, a Star Wars fansite. Leland Chee of the Lucasfilm Story Group verified the spelling and canonicity of the name via his Twitter account. Following the October 23, 2017 airing of the episode "In the Name of the Rebellion", his first appearance since defecting from the Empire, the title of his StarWars.com Databank entry was updated from "Agent Kallus" to "Alexsandr Kallus", marking its first official publication. Filoni stated in the interview that villains frequently lack first names as people do not develop a personal connection with them, but as Kallus' character evolved into a better person, providing him with a first name made him feel more complete. He was named Alexsandr in honor of Alex Spotswood, a member of the Star Wars Rebels crew who consistently voiced Kallus in the "temp recordings" of the script during the show's production, starting from the first season.
While Star Wars Rebels: The Visual Guide indicated that Kallus was in his late 30s upon his arrival to Lothal, suggesting a birth year between 44 BBY and 42 BBY, The Official Star Wars Fact File Part 86 presented a different age. It stated that he was born just a few years prior to the Battle of Naboo and was a teenager during the Clone Wars, which would place his birth around 35 BBY.
The Star Wars Rebels Facebook page asserted that Kallus acquired his bo-rifle from Lasan as a trophy. However, the Rebels episode "The Honorable Ones" later showed that Kallus did not view the weapon as a trophy; instead, he received it as a gift from a Lasat guardsman. This article assumes the Facebook post is outdated and aligns with the events depicted in "The Honorable Ones."