Janek "Tank" Sunber, a childhood friend of Luke Skywalker from their shared upbringing on Tatooine, was known for his imposing physique, earning him the nickname "Tank" among his companions. Raised on a moisture farm, Sunber initially aspired to become an Imperial pilot, but his test results fell short of the required standard. Undeterred, he enlisted in the Imperial Army, where his dedication and diligence led to a swift promotion to lieutenant. Sunber's first taste of combat occurred on Maridun, where his company faced an overwhelming force of Amanin warriors. During the battle, Sunber's work ethic, quick thinking, bravery, and tactical skills impressed his commander, General Ziering. Sunber's strategic acumen proved instrumental in saving the besieged Imperial camp. As Ziering succumbed to his wounds, he lauded Sunber's efforts in his final moments and promoted him to the rank of commander. Sunber successfully led the camp's defenders to victory, but his jealous former superior, Captain Gage, who was now subordinate to him, refused to acknowledge Sunber's promotion after the conflict.
Continuing his military service as a lieutenant, Sunber was later tasked with suppressing the remaining Loyalists on Jabiim. He was disturbed by the enslavement of these individuals by Kalist VI. On Kalist VI, Sunber risked his career to stop another lieutenant from sexually assaulting a slave, but he avoided punishment due to a Rebel attack on the base. Skywalker, his old friend, was among the attackers. Sunber confronted Skywalker, rejecting his pleas to join the Rebellion, as he remained convinced that the Empire represented order and was the righteous side in the Galactic Civil War. Skywalker managed to escape, leaving Sunber injured.
The revelation that Skywalker and their mutual friend, Biggs Darklighter, had become his adversaries deeply troubled Sunber. Unable to reconcile the possibility that he had chosen the wrong path, he ultimately resolved to stop his former friend. He shared his knowledge of Skywalker with Darth Vader and volunteered to capture the Rebel hero. Sunber sent a message feigning his desire to defect and was "rescued" by Skywalker, who brought him into the ranks of the Alliance Fleet. Once there, Sunber attempted to subdue the young Jedi, leading to a confrontation between the two. Sunber had Skywalker at his mercy, but he found himself unable to kill his childhood friend when the ship sustained damage during an attack by Vader's fleet. Sunber found himself clinging to the edge of a precipice, with an unconscious and injured Leia Organa in his grasp. He rescued the Rebel leader, handing her up to Skywalker, before losing his grip and falling into the abyss.

Janek Sunber, hailing from Tatooine, was born into humble beginnings as the grandson of a slave. His upbringing took place on a moisture farm situated in close proximity to Anchorhead. Growing up on Hutt-controlled Tatooine, he acquired fluency in Huttese alongside Basic. He associated with a group of youths from Anchorhead who were close to his age. Due to his larger size compared to the other boys, he earned the moniker "Tank," which became his common nickname. He was known for his mischievous nature, his penchant for breaking rules, and his enthusiasm for having fun. He shared a close bond with Biggs Darklighter and Laze "Fixer" Loneozner, who were a few years older than him and other boys like Windy Starkiller and his good friend Luke Skywalker. During his mid-teens, this age difference led him to spend more time with the older boys, engaging in activities such as racing landspeeders and visiting Tosche Station in Anchorhead. As they matured, he rekindled his close friendship with Skywalker. On one occasion, he "borrowed" his father's blaster rifle to go womp rat hunting with Darklighter and Skywalker.
Throughout his childhood, Sunber displayed exceptional piloting skills, frequently navigating through Beggar's Canyon with his friends. He harbored aspirations of utilizing these skills as an Imperial pilot, envisioning himself as a glamorous and dashing figure. Darklighter and Skywalker also planned to become Imperial pilots, and Sunber was confident that they would succeed and serve together. However, when he applied to the Naval Academy on Prefsbelt IV, his test scores were insufficient to qualify him as a pilot.
Rather than succumbing to disappointment, Sunber opted for a career in the Imperial Army. He departed Tatooine in 1 BBY and underwent training at the Academy of Carida, where his outstanding performance and tactical acumen earned him a transfer to officer training. Within a year, he graduated as a lieutenant. The rigorous training instilled in him the value of discipline, curbing his impetuous nature. As an army lieutenant, Sunber felt envious of his friends, who he believed had chosen an easier path to advancement compared to the less glamorous life of a foot soldier. Nevertheless, he remained determined to make the most of his situation and ascend to a high position.
In the early months of 0 ABY, Sunber received his assignment to the world of Maridun. He found himself under the command of Captain Gage, a young and privileged officer whose rapid advancement, condescending attitude, and aversion to hard work irritated Sunber, who had grown up in a backwater region. During a journey with an armored column, one of the Juggernauts became immobilized. Sunber, a man who believed in leading by example and did not shy away from physical labor, intended to assist the stormtroopers under his command in freeing the vehicle. However, Gage reprimanded him for not maintaining a proper distance from his men. Undeterred, Sunber entered the mud to aid his troops, earning the respect of the expedition's commanding officer, General Ziering, who recognized Sunber's dedication and work ethic.

As soon as the Juggernaut was freed, the column was ambushed by local Amanin warriors. Sunber, experiencing his first combat situation, immediately organized his unit to return fire, quickly repelling the ambushers and earning Ziering's praise for his initiative. Now wary of what had previously been perceived as peaceful natives, the column resumed its journey, with Sunber's squad taking the lead. Before departing, Sunber noticed that the rock on which the Juggernaut had become stuck bore markings that appeared to be Amanin ritual symbols. After a full day of travel, they arrived at a remote mining outpost on the Maridun prairie, only to discover that it had been raided by the Amanin, who had left it in ruins and stolen the miners' blasters. Sunber immediately ordered his men to establish defenses, but Gage countermanded him and brought the matter to Ziering, who suggested that only a small redoubt be constructed against the cliff face along which the outpost was built, as the men were fatigued from the day's march. Undeterred, Sunber worked alongside the stormtroopers to construct the walls. As night fell, he consulted with Gage, Ziering, and Ziering's deputy Commander Frickett. Gage and Frickett expressed confidence in the defenses, but Sunber's doubtful expression prompted Ziering to inquire about the junior officer's opinion. Aware that he was creating enemies by challenging his superiors, he pointed out that they lacked sufficient manpower to defend the position, lacked adequate intelligence on the Amanin, and had no avenue for retreat.
At dawn, the Amanin launched an attack, with climbers descending the cliff face. Sunber, overseeing the defense, was caught near one of the two Juggernauts when it was destroyed by sabotage. Knocked unconscious, he awoke to learn that Ziering had been wounded in the same explosion and was recovering. Frickett and Gage were managing the defense and tasked the impertinent lieutenant with constructing wider perimeter fortifications. Disappointed in his subordinate, Ziering assigned Gage to patrol duty. When Gage's patrol came under attack, Sunber swiftly took control of the remaining Juggernaut and dispersed the Amanin with a quick blast, allowing Gage to return to camp. In their wake, a vast horde of Amanin warriors was revealed. With Ziering undergoing surgery, Frickett assumed command. Panicked, he ordered a charge. Sunber immediately recognized that the Amanin were attempting to lure them into an ambush, but neither Gage nor Frickett listened in time. Frickett was killed in the field, and the last Juggernaut was captured and rendered inoperable.
Following a conference, Ziering held Sunber back and sought his counsel. The younger man acknowledged that without reinforcements, the entire company was likely to perish. Therefore, he proposed that they sell their lives dearly, establishing three successive breastworks with overlapping fields of fire in front of a final redoubt. Impressed, Ziering promoted Sunber to captain and implemented his plan. Sunber spent the night overseeing the construction of trenches and earthworks.
When the time came to mount the defense, Sunber protectively suggested that the general retreat to the redoubt. In his absence, the envious Gage ordered Sunber to the first trench, using his authority as senior captain to place Sunber in the greatest danger. Sunber maintained the morale of his men until sunset, when the Amanin launched their attack. As the natives threatened to overwhelm his trench, Sunber gave the order to retreat to the second trench. He was dismayed to see that Gage, who had been ordered to the second trench by Ziering in retaliation, had faltered upon witnessing the onslaught and ordered his detachment to retreat. Sunber's squad lacked the covering fire necessary for a safe withdrawal. Fearful, he managed to devise what seemed to be the squad's only chance: launching a thermal detonator at the wrecked Juggernaut in the field. He succeeded, igniting the Juggernaut's fuel supply in an explosion that cleared much of the field and delayed the Amanin advance long enough for Sunber to retreat to the second trench.

With no thermal detonators remaining, Sunber needed a new tactic to stall the Amanin. He devised a plan to have his men lower themselves out of sight in the center of the trench as if preparing for an attack, and then move to the north and south ends of the trench. Deceived, the Amanin launched their attack on the center. Sunber's men caught them in a crossfire, while Ziering's redoubt E-webs raked the Amanin caught in the center. Sunber swiftly retreated to the redoubt, where he was warmly greeted by Ziering before a renewed Amanin offensive demanded their attention. The Imperial forces held out for a long time, but the relentless Amanin assault gradually depleted their numbers, and barrages of Amanin throwing spears struck more and more troops. Eventually, Sunber himself was struck in the right shoulder but fought through the pain to remain conscious and engaged in combat. Next to him, Ziering was pierced through the chest. The Tatooinian rushed to the general's aid, but Ziering was beyond help. He passed away after urging Sunber to lead the men to victory and issuing him a field promotion to commander.
Fully feeling the weight of responsibility, Sunber shouted encouragement to his men, who fought with even greater ferocity. At long last, the opposition subsided. Sunber immediately began consolidating his defenses in anticipation of another onslaught, but instead, the Amanin leader approached. Honored by the Imperial valor in what the Amanin perceived as a ritual battle—takital—resulting from the Imperial incursion into sacred lands marked by the stone Sunber had observed, the Amanin chieftain offered peace and a tribute of slaves captured in their battles with other Amanin tribes.
After finalizing the agreement, Sunber filed a report and eventually returned to Carida to face a board of review leading an inquiry into the Battle of Maridun. While losses had exceeded ninety percent of the Imperial force, the board deemed Sunber's actions satisfactory and the acquisition of slaves for the Empire quite advantageous; they issued Sunber a special commendation. However, due to Gage's envious refusal to verify Ziering's field promotions, Sunber was demoted back to lieutenancy.

Approximately seven months later, Sunber was assigned to a detail tasked with assaulting an underground fortress belonging to Jabiimi Loyalists, which had proven impervious to Imperial bombardment. Sunber led a charge up a rocky hill against the well-fortified enemy. He directed his engineers in creating a breach in the rock, exposing an entry point into the Jabiimi base. With access gained, he was able to force the defenders to surrender. In accordance with his orders, he oversaw the enslavement of the rebels, but he felt uneasy about the task.
Boarding the same Acclamator-class assault ship as the slaves, Sunber and his remaining men—all clones—shipped out to Kalist VI. There, he secured a new unit assignment and found himself in empty quarters. His belongings had been lost in transit, but he was accustomed to such inconveniences. As he unpacked his new kit, he was challenged by another officer, a burly man named Clynn, who claimed the room as his. Rather than backing down, Sunber earned the respect of the other officers by standing up to Clynn and, when Clynn attacked, subduing the larger man. Captain Kale Roshuir intervened and assigned Sunber and Clynn to immediately work double shifts together.
Impressed by Roshuir's mention of Sunber's service at Maridun, Clynn eagerly showed the new man around the base as they supervised the slave workers. Imperial media had glorified the survivors of Maridun, and Clynn was eager to hear anecdotes. However, Sunber viewed battle as anything but glamorous. After their shifts concluded, Clynn promised to show Sunber entertainment, although the veteran of Maridun simply wanted to sleep. Sunber was shocked by Clynn's idea of entertainment when the larger man pulled away a female prisoner and dragged her to a cell. Outraged, Sunber demanded that Clynn stop. When he was ignored, Sunber drew his blaster on the other officer and forced him to release the woman. Clynn left, threatening Sunber with retribution.
Clynn reported Sunber to Roshuir, claiming that Sunber had drawn a weapon on him while interfering with the disciplining of a prisoner. However, before Roshuir could address the matter, the captain was summoned to lead an expedition against a suspected Rebel base at Thila. He left Sunber at the base and promised to bring him up on charges upon his return. Sunber, now experienced in military politics, knew that a tribunal would not rule in his favor. Worried, he was suddenly relieved by the unexpected appearance of Skywalker on the landing platform from which Roshuir had departed. Skywalker, wearing a lieutenant's uniform, was equally surprised, and Sunber excitedly engaged in reminiscing with him, updating his old friend on his own life and inquiring about the careers of Skywalker and Darklighter. He was proud to hear Skywalker report that he had become a pilot, as had Darklighter, but devastated to learn that Darklighter had died at the Battle of Yavin, sacrificing himself to protect Skywalker. Sunber began to express his doubts about the Empire and its role in slavery, and to his surprise, Skywalker responded that he had doubts as well. However, Sunber was shocked when Skywalker suggested that he join the burgeoning Rebel Alliance. When a transmission from command announced that Rebel saboteurs were on the base, Sunber realized that his old friend was one of the enemy. When a nearby explosion occurred, Sunber attempted to apprehend Skywalker, but the other man knocked the Imperial officer unconscious.

Upon regaining consciousness, Sunber was filled with outrage and betrayal. He immediately reported the presence of saboteurs and provided a description of Skywalker before pursuing him into the slave quarters. There, he discovered that the slaves were gone and stormtroopers had been killed. Enraged, he caught up with Skywalker as he was leading the slaves aboard the Acclamator. Confronting his old friend, he was taken aback when Skywalker left himself vulnerable, confident that Sunber could not shoot him. Instead, the budding Jedi expressed his conviction that Sunber would recognize that rescuing the slaves was the right thing to do and would not stand in the way—as did the woman he had previously rescued from Clynn's advances. Sunber admitted that Skywalker was right and agreed to let the slaves go, although he refused to defect, believing that he was accomplishing good within the Empire. When another detachment of Rebels, accompanied by the freed Rebel Jorin Sol, arrived, Sunber again felt betrayed and manipulated, used by Skywalker to further a Rebel agenda that had nothing to do with slaves. Enraged, he fired on Sol, but Skywalker's lightsaber deflected the bolt, sending it back into Sunber's shoulder. Skywalker once again tried to persuade Sunber, but Sunber remained unmoved, although shocked when Skywalker revealed that he had destroyed the Death Star, and Darklighter had been a Rebel as well. Skywalker and the Rebels departed, leaving Sunber wounded on the hangar floor.
Following the battle, intelligence officers convinced Roshuir not to charge Sunber—secretly grateful that Sol, whom they had broken and turned into a spy, had been returned to the Alliance Fleet. Bacta treatment healed his shoulder, and Sunber was left with only the emotional wounds of having his two best friends on opposing sides of a war. This internal conflict consumed his thoughts over the next month, even as he commanded in a hard-fought battle against a Rebel base on Keskin. The night before, he had a dream in which he and the other Anchorhead youths were children playing war, and in it, he had "killed" Skywalker. Although tormented by the situation, Sunber increasingly believed that he was destined to stop Skywalker. Even when he was nearly killed by an infiltrator's thermal detonator, Sunber felt confident that he would not die, as Skywalker was not present. Thrown by the blast, he struggled with and killed another Rebel warrior before making his way back to Imperial lines, which were withdrawing in preparation for a TIE bomber bombardment. One of the bombers was shot down and hurtled toward Sunber. As it tumbled toward him, barely missing his head, Sunber initially accepted death but then realized that he would survive after all—and knew that he did so to battle Skywalker.
Later, Sunber interrupted the beating of a prisoner from the battle in an interrogation room, reprimanding the Imperial soldiers for taking out their anger on a captive. He was determined to demonstrate to the Rebel that the Empire truly represented justice and order. The prisoner remained unconvinced, hostilely proclaiming that the Empire would fall and mentioning Skywalker as the Rebellion's foremost hero. The prisoner's taunting with Skywalker's name was enough to cause Sunber to snap, striking the man until he was pulled away by the very men he had threatened with charges for beating the prisoner. To learn that Skywalker was not only a Rebel but also a leading Rebel warrior, the hero of Yavin, was too much for Sunber to bear.

That night, Sunber was again sleepless, tormented by Skywalker's role in the Rebellion. He refused to accept that Skywalker could have been right to join the Rebellion and realized that, as a major Rebel figure, Skywalker possessed important background information. His sense of duty compelled him to report it. Sunber was taken to the Star Dreadnought Executor and brought before Darth Vader. He provided Lord Vader with a full report of Skywalker's background, which piqued Vader's interest, and Vader decided to exploit Sunber's connection to the young Rebel.
Sunber agreed to become a mole within the Rebel forces. He sent a message to Skywalker stating his desire to defect and providing coordinates where he could be found. The message was crafted to appear as if he had been discovered, and Sunber consented to undergo torture at the base at the given coordinates—a small space station controlling a deep-space junkyard—to strengthen his cover and credibility. Rebel commanders were skeptical of the message, but Skywalker, trusting his friend implicitly, dismissed concerns that it could be a trap and embarked on an unsanctioned rescue mission with supply clerk Deena Shan.
Skywalker located Sunber in a torture chamber on the deserted station, and Sunber warned him that he had been "found out" and that the situation was indeed a trap. Roshuir led a boarding party of stormtroopers onto the station, trapping Skywalker, Sunber, and Shan in a firefight in a hallway. At Roshuir's urging, Sunber attempted to capture Skywalker, but a stray shot struck him in the hand, halting the capture attempt before it could begin. Skywalker managed to fend off the troops, and the wounded Sunber accompanied them as the two Rebels escaped the ambush.
Upon their return to the Alliance Fleet, Sunber was taken into custody to receive medical attention. He was subjected to repeated interrogations by Rebel spymaster Tungo Li, who found no inconsistencies in his story. Eventually, Sunber was granted limited freedom, kept away from sensitive areas of the ship and always guarded by at least one Rebel. He reunited with Skywalker, but by then, he had firmly concluded that Skywalker was an enemy of the Empire, an enemy of order—a decision reinforced by Skywalker's seemingly nonchalant dismissal of the loss of life in the Death Star's explosion. Still, he could not entirely bring himself to hate his old friend.

That evening, a vision of Vader invaded his sleep, commanding him to cast aside all hesitation and seize Skywalker for the Dark Lord of the Sith. Driven by this spectral encounter, he snapped awake, subdued the guard stationed outside his quarters, pilfered the man's attire, and stealthily infiltrated Rebel One. Concurrently, Sol unleashed a barrage of blaster fire upon Leia Organa on the ship's command deck, as Vader's formidable fleet materialized. Sunber, pressing onward towards the bridge, leveled his weapon at Skywalker. The Rebel implored Sunber to permit the wounded Organa to receive urgent medical attention, but Sunber remained unmoved. He commanded Skywalker, burdened with Organa, to proceed towards an escape pod destined for Vader's retrieval; thereafter, he pledged to ensure the Rebel leader's treatment. Skywalker, deeply disillusioned, revealed to Sunber that the Empire was responsible for the deaths of Owen and Beru Lars, his adoptive parents. Overwhelmed by emotion, Sunber lashed out, striking Skywalker, prompting the Jedi to retaliate. Sunber gained dominance, holding Skywalker at his mercy, threatening to end his life, but he found himself unable to carry out the act. Skywalker proposed surrendering to capture if Sunber would guarantee Organa's survival. Before Sunber could act, an explosion reverberated through Rebel One, triggering a malfunction in the ship's artificial gravity, transforming the corridor into a treacherous abyss. Sunber clutched onto Organa and was, in turn, grasped by Skywalker, who was securely positioned atop a horizontal surface. Having relinquished his desire to fight Skywalker, he summoned all his remaining strength to hoist Organa up to the other man before losing his grip and plummeting into the depths of the extended hallway.
While Sunber's remains were never located onboard Rebel One, it was noted that prior to Rebel One's jump to hyperspace to evade the ambush, a single escape pod was launched and subsequently recovered by Imperial forces.
In his youth, Janek Sunber yearned to escape Tatooine, become an Imperial pilot, and achieve prominence within the broader societal structure. When this aspiration proved unattainable, he channeled his ambitions into the infantry rather than returning home in disgrace, his dreams of glory shattered. He harbored envy for Darklighter's and Skywalker's roles as pilots, yet he felt pride in them and held unwavering confidence in his friends' achievements. Sunber discovered his own path to success as an infantry officer, earning the respect of the seasoned General Ziering, who hailed him as "a natural" in command.

Sunber was characterized by his strong work ethic. Displaying a willingness to undertake any task demanded by the situation, he would toil tirelessly or risk his life for the Empire, and he preferred to avoid assigning his subordinates tasks he himself would not undertake. Once a rebellious and impetuous youth, Imperial training instilled in him a deep appreciation for personal discipline and order. The crucible of combat experience accelerated his maturation. He held a firm belief in duty, dedicating himself entirely to its fulfillment. Despite his unwavering loyalty to the Empire and his perception of it as an orderly and just system, he harbored reservations about certain Imperial practices. The act of slave-taking particularly troubled him, given his grandfather's history as a slave, yet he dutifully executed his orders nonetheless. He attempted to justify Imperial slavery as a consequence borne by those who resisted, but he remained unconvinced of its inherent justice. Upon witnessing a fellow officer's attempt to sexually assault a prisoner and rationalize it as customary, Sunber, in a fit of rage, drew his blaster, determined to prevent such an injustice.
Upon learning that Skywalker and Darklighter had aligned themselves with the Rebellion, Sunber was devastated and felt a sense of betrayal, grappling with the fact that his friends had become his adversaries. He reminisced about the fond memories they had shared, which only intensified his sense of betrayal at their decision to oppose the Empire, engaging in violence against its soldiers and obstructing the establishment of order. He sometimes questioned whether Skywalker and Darklighter had made the correct choice—but swiftly suppressed such thoughts, as he could not reconcile with the possibility that he had dedicated his life to a misguided cause, desperately clinging to the notion that the Empire was the harbinger of peace and stability to the galaxy. Instead, Sunber came to the conviction that he was somehow destined to thwart Skywalker. However, Sunber never quite managed to bring himself to kill Skywalker when presented with the opportunity, and ultimately opted to rescue Leia Organa before he fell away from Skywalker during their confrontation, thereby avoiding the need to make a definitive choice.
The character "Tank" was initially referenced in Star Wars: Episode IV A New Hope and its comic adaptation as a friend of Luke Skywalker who had departed for the Academy, yet despite this distinction, he received minimal attention within the Expanded Universe for a period of twenty-seven years. In 2004, the comic arc Star Wars: Empire: To the Last Man was released. Penned by Welles Hartley and brought to life by Davidé Fabbri, it centered around a character identified as Janek Sunber as its protagonist. Allusions were made to Sunber's humble origins, his aspiration to become a pilot, and his friendships with fellow pilots, but no explicit connection was established between Sunber and "Tank". In the subsequent arc Star Wars: Empire: The Wrong Side of the War, also crafted by Hartley and Fabbri, Sunber was revealed to be "Tank" and positioned as being in conflict with Skywalker. This revelation was not a retcon, but rather a connection that had been intended from the outset of Sunber's creation. Star Wars: Empire transitioned into Star Wars: Rebellion following that arc, and Sunber's narrative was continued in Star Wars: Rebellion: My Brother, My Enemy, which depicted Sunber confronting Skywalker but concluded with Sunber's fate and allegiance unresolved. My Brother, My Enemy marked the first Sunber story that did not involve Hartley and Fabbri; instead, it was written by Rob Williams and illustrated by Brandon Badeaux and Michel Lacombe.