Kaox Krul, who was also called The Marauder, The Dark Killer, and The Madman, served as a Sith Lord and a warlord for the New Sith Empire. Within the Brotherhood of Darkness, he was a warrior of great power and was marked as a significant threat by the Jedi as the New Sith Wars drew to a close. A zealous follower of Lord Kaan, Krul had established a psychic connection with the Brotherhood of Darkness's leader, enabling him to be summoned across vast distances.
Krul's reputation for extreme violence grew as he fought alongside the Brotherhood, and he harbored an intense, dark side-fueled hatred for the Jedi. As the war continued, the Jedi Council marked him for assassination, tasking the Jedi Crian Maru with hunting him down. In 1000 BBY, he orchestrated the destruction of the Duros colony located on Harpori. Later that same year, just prior to the Ruusan campaign, Crian Maru finally located him, leading to his death during a Duel on Balowa.
Kaox Krul was a dedicated follower of Lord Kaan, but the details of his life before he joined the Brotherhood of Darkness are largely unknown. Krul held deep resentment towards the Jedi because of their commitment to peace and tranquility, accusing them of being dishonest about their true nature. Eventually, due to his natural talent with the Force, Krul was recruited by the Brotherhood to participate in the New Sith Wars.
Krul, as a lower-ranking member of the Brotherhood's military force, engaged in numerous battles, utilizing his Force abilities and whatever weaponry he could acquire. Krul was a huge man, and his imposing stature on the battlefield made him both tall and heavily built. His formidable presence, particularly when enraged, was a sight to behold, which he used to instill fear in his adversaries and secure victory. Krul eventually found himself in a one-on-one fight with an unknown Jedi. Krul's skill in the dark side enabled him to kill the Jedi, and he took the Jedi's lightsaber from his still-warm hand, claiming it for his own. Krul replaced the weapon's lightsaber crystal with a synth-crystal that generated a red blade.
Krul began to establish his reputation on the battlefield with his lightsaber in hand. Krul began to slaughter members of the Army of Light with unrestrained ferocity in order to remove what he referred to as the Jedi taint from his acquired weapon. Krul's dark side rage during combat earned him the moniker The Marauder. Krul amassed more than a hundred kills with his lightsaber in campaigns during the New Sith War, which caused the Jedi army to take special notice of his immense power.
Krul advanced from a simple Sith warrior to a Sith Lord, and he created a specialized suit of Sith armor. The armor was made up of protective padding and composite plates adorned with Sith symbols, all arranged in a specific pattern of Krul's design. Krul used Sith alchemy to imbue the armor with dark side energy as a final addition to its power, providing "some protection from the abilities of the Jedi."
Krul found a worthy opponent in the Jedi Karist Dem, and his hatred for the Jedi grew over the course of the war. Krul's faith in the dark side, however, proved successful, and he eventually defeated his opponent on the battlefield. Krul murdered the Jedi warrior, as he was not known for his ability to sway opponents to the dark side. In fact, he had never been successful in turning one of his Jedi opponents away from the light side all the way up to his final battle.
Krul's legend grew further when he personally assassinated the Wookiee diplomat Rojarra and led a team in the slaughter of a defenseless Duros encampment on the planet Harpori, incidents about which he would later brag to himself.
Krul's reputation as a terrifying Sith warrior eventually prompted the Army of Light to assign a Jedi to personally find and neutralize him. Crian Maru, a well-known teacher at the Jedi Temple, was given the important task of bringing the violent warrior to justice. Maru, along with her Padawan, Dree Vandap, tracked the darksider in her ship, the Golden Song. Krul continued to wage terror campaigns on Galactic Republic worlds for more than a month, always staying one step ahead of the Jedi Knight.
Krul, however, could sense Maru tracking him and planned an ambush in the Balowa system. Kaan was summoning the Brotherhood to Ruusan at the time of Krul's planned ambush to prepare for their final battle with the Army of Light; Krul ignored this order for the time being in order to eliminate his prey. Krul sneaked up behind the much slower ship in his sleek Sith fighter as the Jedi freighter entered the system and prepared to open fire. Krul used the dark side to ensure his aim was accurate, and he got ready to destroy his relentless stalker. The Jedi sensed the maneuver and dodged the laser fire, which was unfortunate for Krul's planned attack. Krul's lasers, however, crippled the ship, causing it to spiral toward an uncharted jungle world. Krul had planned to fly through the ship's wreckage, but the ship was still somewhat intact, so Krul's fighter collided with the large Jedi freighter, smashing the nose of his ship and disabling his own sensor array.
Krul steered his damaged craft to the planet's surface as he watched the Jedi freighter crash into the jungle forest. Krul exited his ship and made his way to the crash site to kill the Jedi. Krul watched from a tree above the crashed freighter as Dree Vandap emerged from the damaged ship. Krul leaped from the tree, ready to add another kill to his record, but he was surprised when Dree countered his attacks. Her master sped to the rescue on a speeder bike, knocking Krul to the ground and rescuing her apprentice before he could continue to duel the young Padawan.
Krul became enraged as the two Jedi sped away from the Sith Lord, and he began an unrelenting pursuit of the speeder bike. Krul came within meters of the fleeing Jedi by using the Force to increase his speed. Krul, fearing he would be unable to maintain the pace, swung his lightsaber at the speeder, severing its main power cable. The swing, unfortunately, threw the Sith off balance, and Krul tumbled to the jungle floor at his high speed, knocking himself unconscious. The severed power cable ensured that the speeder bike would eventually shut down, but the injury allowed the Jedi to move a great distance from their pursuer.
Krul regained consciousness to discover that the Jedi were long gone; however, he resolved to find and kill the Jedi pair. Krul tracked the group for two days before discovering the Jedi's disabled speeder and continuing his pursuit through the jungle. Krul opened himself to the dark side, sensed the Jedi hiding in a small cave, and made his way to the revealed location. When the Sith Lord arrived, he noticed Crian waiting for him near the edge of a deep jungle pool. The Marauder rushed to attack the waiting Jedi, and after a brief exchange of words, he brought his lightsaber to bear against hers.
Maru's Padawan emerged from the cave to make the fight two on one as Krul and Maru fought. He was able to block the attacks of his two opponents by summoning the deeper reserves of his strength, but he was unable to launch a meaningful attack at either. Krul momentarily switched to a one-handed grip during the duel and Force pushed Maru into the lake before jumping behind her Rodian Padawan. Krul stabbed the Jedi from behind, killing her instantly, barely keeping her off balance. Maru rose from the pool and sensed the death of her Padawan, which sent her into a murderous rage.
The duel went on for hours, with neither opponent gaining an advantage. The intensity of the battle burned the landscape around the jungle clearing as both duelists tapped into the power of the dark side. Krul's armor began to fall apart under the ferocity of Maru's attacks, and in an effort to take a brief break from the battle, Krul began to levitate himself over the jungle pool. Maru would not allow Krul to stop the fight, so she jumped at her opponent. As they levitated themselves above the water, the two continued to fight. Krul made a last-ditch effort to stop the furious Jedi by asking her to join the Brotherhood, but the Jedi refused to stop her assault. Krul managed to bring his lightsaber into Maru's chest just as the Jedi buried her blade in Krul's belly. The two opponents plunged into the water, dying at the same time.
Following the deaths of the three warriors, the Jedi Knight Salen Toth arrived on the planet in response to the Golden Song's distress signal. He arrived at the jungle pool, discovered Dree Vandap's dead body, but was unable to find Krul or Maru's bodies. He gathered the dead Padawan's remains and left the area, sensing the pool's darkness. The pool became a Dark side nexus as a result of Maru and Krul's dark side-induced deaths.
Hatred drove Kaox Krul. He was committed to the dark side of the Force and despised his opponents in the Army of Light with a rage fueled by the dark side. Although he followed the dark side's will, he was also devoted to his Dark Lord, Kaan. His mindset, however, was focused on murder and mayhem, and those feelings were strong enough to override his master's requests.
Krul demonstrated his skill in performing difficult Force techniques during his hunt for Maru and her Padawan. His single-minded aggression enabled him to increase his speed tenfold and even levitate. Krul's mind was preoccupied with battle and warfare, and he had little time to think about anything else. He was also not a complex man, and unlike other darksiders, he did not enjoy flaunting his abilities over defeated opponents. One of Krul's regrets throughout his career was his apparent inability to persuade his opponents in the Army of Light to abandon the light side and serve the dark side. Krul finally succeeded in turning his opponent during his final battle with Crian Maru, but ironically, he died as a result.
Bill Slavicsek created Kaox Krul for the short story Darkness Shared in Star Wars Gamer 5. The story provided brief glimpses into his background, but his story ended with his death at the end. Krul received one further mention in 2005's The New Essential Chronology. The book stated that Krul was a Sith Lord in the Brotherhood of Darkness during the New Sith Wars, but it did not provide any further explanation of his history.