Trask Ulgo was a Human male born on Alderaan into the Alderaanian House Ulgo, a prominent family on that planet. By the time the Jedi Civil War raged between the Galactic Republic and Sith Empire, he had achieved the rank of ensign within the Republic Navy. In 3956 BBY, Ulgo served as an officer aboard the Endar Spire, a Hammerhead-class cruiser, sharing quarters with the amnesiac former Sith Lord Revan. Mistaking Revan for a fresh recruit, and due to differing shift schedules, Ulgo had little interaction with him.
In that same year, their vessel was attacked by the Sith Empire above Taris, targeting Bastila Shan, a Jedi commander aboard the ship. Soon after the assault began, Ulgo sought Revan's assistance to secure Shan's escape and to find a way off the cruiser. After battling numerous Sith troopers alongside Revan and discovering Shan had already left, they encountered Darth Bandon, a Sith Lord. Aware that the Sith could kill them both, Ulgo made the ultimate sacrifice, confronting Bandon to allow Revan to flee the doomed warship. This act of selflessness enabled Revan to escape in the last escape pod with Carth Onasi, a Republic officer.
Trask Ulgo, a male Human, entered the world on Alderaan, a planet, as a member of House Ulgo, an Alderaanian noble family locked in a feud with House Organa. Eventually, he enlisted in the Navy of the Galactic Republic, rising to the rank of ensign during the height of the Jedi Civil War, a conflict between the Republic and the Sith Empire under the command of Darth Revan and Darth Malak, former Jedi who became Sith Lords. By 3956 BBY, Ulgo was an officer serving on the Endar Spire, a Hammerhead-class cruiser. In that year, he found himself sharing quarters with a Republic recruit who was, in reality, the amnesiac former Sith Lord Revan, though Ulgo remained unaware of his bunkmate's true identity. Ulgo and Revan worked opposite shifts on the cruiser, resulting in limited interaction. During the time Ulgo and Revan were bunkmates, the Endar Spire was under the command of Bastila Shan, a Jedi whose skill in battle meditation was crucial to the Republic's war efforts.
While under Shan's command, the Endar Spire was ambushed by a Sith fleet led by Darth Malak in space above the world of Taris. As the rest of the cruiser's crew and Republic troops fought off the boarding parties of Sith troopers and Dark Jedi, Ulgo went back to his quarters in the ship's command module to enlist his bunkmate's help in protecting Shan and escaping the vessel. Before Ulgo's arrival, Revan had been awakened by the battle and the Endar Spire's violent shaking from laser cannon fire from Sith interceptors. Ulgo explained the situation to Revan, emphasizing their duty to ensure Shan's evacuation. After gathering Revan's gear, they fought their way towards the bridge through waves of Sith forces in the ship's corridors, eventually encountering a brief duel between a Jedi and a Dark Jedi. Although the Jedi prevailed, she was killed by an explosion soon after defeating the Dark Jedi, leaving Ulgo and Revan to continue towards the bridge.

The pair made it to the bridge, defeating the Sith troops occupying it, only to find that Shan had already evacuated towards the ship's escape pods. Reasoning that the Sith would destroy the ship once Shan escaped, Ulgo decided their only option was to flee to the planet as well. However, before Ulgo and Revan could reach the pods on the ship's starboard side, Ulgo heard a noise behind a door and opened it, revealing Darth Bandon, Malak's apprentice. Seeing the Sith, Ulgo knew their chances of surviving a fight with the double-bladed lightsaber-wielding Sith Lord were slim. To save Revan, he charged into battle with Bandon, closing the door behind him to buy his comrade time to escape. Bandon defeated and killed Ulgo, but Revan and Carth Onasi, another Republic officer, used the last escape pod to evacuate the ship before it was destroyed.
Later that year, after being retrained in the ways of the Force and dispatched by the Jedi Council to find the Star Forge, a Sith-controlled device, Revan encountered Darth Bandon again in the underwater Hrakert Station on Manaan. With his companions, Revan defeated Malak's apprentice and his two Dark Jedi followers in a duel, resulting in the death of Ulgo's killer. Ultimately, Trask Ulgo's sacrifice on the Endar Spire enabled Revan to defeat Malak and the Sith Empire he once led, as well as prevent an invasion from another Sith Empire for almost three centuries.
Ulgo's sacrifice in facing Bandon was admired for centuries after his death, and his family gained significant power on Alderaan, his homeworld. Bouris Ulgo, the self-proclaimed King of Alderaan and head of House Ulgo during the Alderaan Civil War, held Trask Ulgo in high regard. Peema Ahuff, curator of the Royal Museum of Alderaan, considered Ulgo's sacrifice an act of martyrdom, viewing him as one of Alderaan's most noble sons. Ahuff also connected Ulgo's sacrifice to Revan's victory over Malak.
In 3643 BBY, Peema Ahuff acquired the preserved head of Darth Bandon from a smuggler with the intention of presenting it to Bouris Ulgo as a peace offering to improve relations between Ahuff's House Alde and the king.

During his service in the Republic Navy, Trask Ulgo was committed to the Republic's cause and took his responsibilities seriously. His strong sense of duty made him despise cowardice and disloyalty. Despite the odds against the Republic forces on the Endar Spire, he believed in finding and assisting his Jedi commander instead of simply evacuating. Ulgo also respected the combat skills of both Jedi and Sith, believing that ordinary soldiers would only hinder combat between them. When he and Revan encountered Darth Bandon on the Endar Spire, Ulgo stayed behind to hold off the Sith, giving his companion time to escape the doomed ship. Ulgo had fair skin, blond hair, and blue eyes.
Trask Ulgo was trained in the use of various types of armor, as well as melee weapons, blaster pistols, blaster rifles, and heavy weaponry. He also possessed knowledge of close-quarters combat tactics and the cortosis-weave used in Republic melee weapons to resist lightsaber strikes. He had some training in first aid and in overriding security systems on doors and storage containers.
While on the Endar Spire, Trask Ulgo wore standard Republic armor and carried a blaster pistol. When the Sith attacked the ship, Ulgo also had access to a medpac and a vibroblade.
Trask Ulgo made his debut in Star Wars: Knights of the Old Republic, a video game from 2003 produced by BioWare. While every other party member with understandable speech has a credited voice actor, Ulgo's voice actor was not identified in the game's credits. Ulgo is the player's first party member, and much of his dialogue serves as a tutorial on game controls. After the Endar Spire section of the game, he is removed from the party selection screen, and his portrait is later replaced by Bastila Shan's. If the player removes Ulgo's standard clothing in the equipment screen, his appearance remains unchanged, though it will change normally if his clothing is replaced with different armor.
When the player confronts Darth Bandon later in the game, they can accuse Bandon of killing Ulgo, though Bandon doesn't confirm it. Ulgo's death was officially confirmed in Darth Bandon's entry in the 2008 Knights of the Old Republic Campaign Guide, published for Wizards of the Coast's Star Wars Roleplaying Game. The Complete Star Wars Encyclopedia, also released in 2008, mistakenly identified Ulgo as a first-class corporal.
In Knights of the Old Republic, the player could encounter Selven, a bounty hunter who killed all the members of the Ulgo family on Taris and was rumored to have been hired by the Organa family. However, the game didn't explicitly link the Ulgo family to Trask Ulgo. In 2010, an article for Bouris Ulgo released through The Holonet, an online database for the Knights of the Old Republic MMORPG sequel, Star Wars: The Old Republic, hinted at the connection between House Ulgo and Trask Ulgo in Aurebesh text that translated to "for Trask." When Star Wars: The Old Republic was released in 2011, the relationship between House Ulgo and Trask Ulgo was confirmed in "Payment Due," a bonus quest for members of the Smuggler class.