Shortly following the Battle of Endor, a human male named Utoxx Prentioch rose to power as a warlord, leading a fleeting breakaway faction that splintered from the Galactic Empire. During the final years of Galactic Emperor Palpatine's rule, Prentioch held the position of vain and ambitious Moff of the Sombure sector. Upon learning of Palpatine's death at the Battle of Endor, he began to solidify his authority within the sector. Within a matter of months, Prentioch began to operate independently of the Galactic Empire, governing the Sombure sector under his own authority. Citing ancient surveys and treaties that purportedly demonstrated a larger Sombure sector, Prentioch initiated invasions of neighboring sectors to expand his dominion, with the aspiration of eventually ruling the entire Empire.
However, Prentioch's ambitions were thwarted by his entanglement in a conflict with a rival warlord, Moff Eyrgen, for control of the Wornal sector, which prevented Prentioch's Dominion from achieving significant size. The New Republic largely disregarded his existence during their push into the Core Worlds, and Prentioch's war with Eyrgen depleted his resources. In 6 ABY, Prentioch's attempt to secure the food exports of the planet Kaal to supply his forces failed. Later that year, the Republic forces defeated and captured him during the siege of Bomis Koori, marking the end of his reign and the collapse of his domain.
Under the Galactic Empire, the Human male known as Utoxx Prentioch achieved the rank of Moff in the Sombure sector. The ambitious Moff Prentioch began to take personal control of his territory when Emperor Palpatine met his end at the Battle of Endor in 4 ABY, and the Empire started to fall apart. He succeeded in swaying his military subordinates, who transferred their allegiance to him. Prentioch, driven by a desire to enlarge his territory, started looking through old treaties and surveys in order to find reasons to include more worlds in the Sombure sector. He replaced his simple Moff's uniform with fancy robes similar to those worn by Imperial Advisors, acting as if he was better than everyone else. While he initially claimed to be loyal to the main Empire as he worked to strengthen his own position, he soon completely rejected Imperial control, becoming one of the numerous warlords vying for power as the Empire's power diminished and the New Republic, which was created from the Alliance to Restore the Republic, grew. Although his position wasn't yet solid, he envisioned himself seizing control of the entire Empire and saw himself as a possible candidate for the Imperial throne.
Prentioch, dissatisfied with simply controlling the Sombure sector, sought to acquire more territory and invaded several adjacent sectors, employing dubious historical claims to justify the expansion of his dominion. Sander Delvardus, another breakaway warlord and one of Prentioch's rivals, opposed these advances. His Mid Rim breakaway state, Prentioch's Dominion, quickly became one of the most important warlord states. Within months after the Emperor's death, he faced competition for control of the region. As his forces advanced into the Wornal sector, he discovered that he had to fight another warlord, Moff Eyrgen. New Republic agents made the conflict worse by giving both warlords false information in an effort to encourage conflict within the Empire. The war between the two warlords who wanted to expand their territory lasted for two more years, using up a lot of Prentioch's resources.
Six months after Palpatine's death, Prentioch ordered his forces to pursue the Black Curs after the mercenary group scouted the Core in preparation for a potential New Republic offensive. Even though two regular Imperial Star Destroyers commanded by Imperial Advisor Bregius Golthan were already pursuing the Black Curs, Prentioch wanted to obtain the mercenaries' reconnaissance data, believing it would help him in his ongoing conquests. Prentioch's two Star Destroyers engaged the Imperial force over Moorja as the Black Curs' Last Chance crash-landed on the planet. However, neither side's ground forces were successful in capturing the Black Curs, and the group managed to escape Prentioch's grasp.
The New Republic, which was rapidly expanding, demonstrated its strength early on by destroying the pirates near Eiattu 6. Prentioch remained within his relatively small holdings, preoccupied with his expansionist wars and reluctant to engage the New Republic. The military of the New Republic bypassed Prentioch during its advance, securing Moorja while Prentioch continued to struggle in the Wornal sector.
Prentioch became involved in negotiations with Tirgee Benyalle, a casino magnate and crime lord who had seized control of the independent world Kaal, for that planet's aquacultural produce in 6 ABY. Prentioch, who had few agricultural worlds under his control, was running low on food and desperately needed supplies from Kaal, which was located near his territories. In this effort, he faced competition from Admiral Kermen, who represented the Empire; a group of New Republic agents; and the purported Syndic Pandis Hart, the chief purchasing agent for the Sif-Uwana Council, who was actually the crime boss Talon Karrde in disguise.
Prentioch left his flagship, the Prentioch, in orbit, facing off against Kermen's Belligerent, and stayed in the Grand Imperial casino and hotel with the other parties involved in the negotiations. Not willing to leave the outcome to chance, Prentioch hired a group of bounty hunters to assassinate his rivals at the summit. While waiting for the New Republic delegation, the last group to arrive, he spent his time gambling and lost terribly at Trin sticks. During a game, an indiscreet adviser approached him and revealed that the bounty hunters had arrived and wanted to discuss payment, enraging the warlord. He stormed out of the casino and secretly met with the bounty hunters at the spaceport, where he settled the matter with their leader. That night, after the New Republic delegation arrived, Benyalle invited all the parties to a private, high-stakes game of sabacc, which Prentioch attended.
That same night, Prentioch's bounty hunters attacked the New Republic negotiators in their room, but failed to kill them. The following morning, Benyalle took the warlord and the other parties on a cruise on her sail barge. They visited a floating harvester factory for the aquaculture industry, which Benyalle showed them around. After the tour, the representatives went to the meeting room of Benyalle's barge, where she outlined her terms. Prentioch was the first to make an offer: a very low price of five hundred credits per ton of food; payment for the construction and crewing of ten more harvesters, doubling Kaal's aquaculture capacity; and ten million credits to sign the deal. Kermen, the last to speak, announced his intention to seize the entire operation by force. His stormtrooper bodyguards, along with the operatives with whom he had replaced most of the sail barge crew, attempted to take control of the barge, but loyal crewmen and the other delegates fought back. Prentioch summoned reinforcements from his Star Destroyer overhead, which had engaged Kermen's Belligerent. As Karrde, the New Republic agents, and Benyalle fled with Karrde's allies on a submersible, a dropship full of Prentioch's troops arrived to fight Kermen's operatives. Prentioch barely escaped as the sail barge was destroyed in an explosion Karrde arranged to cover his flight. He lost the opportunity to sign the deal, as Benyalle agreed to a contract with the New Republic delegates who had saved her life.
Later that year, Prentioch's reign finally came to an end. The New Republic advanced from Moorja to Prentioch's Dominion and engaged Prentioch's forces in the decisive siege of Bomis Koori. Prentioch's military forces could not withstand the forces of the rising government, and Prentioch was captured. With its leader in New Republic custody, Prentioch's personal empire collapsed, swept away by the New Republic's campaign for galactic control.
Utoxx Prentioch was driven by ambition and lacked loyalty, prioritizing his own glory as a warlord over remaining a part of the Empire. A man who sought to elevate himself, Prentioch named his flagship, the Prentioch, after himself, and as a warlord, he wore robes reminiscent of those worn by an Imperial Advisor, one of the highest positions in the Empire. Prentioch was a proud man who became irritated when those he considered inferior challenged his abilities, and he had a tendency to look down on others. In his own mind, he was a great person, one of the most important individuals in the galaxy, always correct, and obviously the best at everything he did. He considered himself an expert in games of chance like Trin stick and sabacc, even though he didn't actually know how to play, and he refused to admit that he didn't know what he was doing.
Prentioch demanded excellence and extreme deference from his subordinates. He did not tolerate failure or disagreement. When things went wrong for him or a subordinate disappointed him, Prentioch would lose his temper and fly into a violent rage.
The character Utoxx Prentioch was first mentioned as "Moff Prentioch" in an adventure idea within the article "Recon & Report: The Journey to Coruscant" in Star Wars Adventure Journal 2, which was published in 1994. His first name, Utoxx, was revealed fifteen years later with the publication of The Essential Atlas. In the intervening years, Prentioch appeared as a character in the Adventure Journal adventure "The Kaal Connection."