Tarsten was a Sergeant within the Sith Empire during the Galactic War. He was a male Human.
Around 3637 BBY, Tarsten joined the clandestine Order of Revan. He collaborated with fellow Revanites Darth Arkous and Lord Goh to secure the Tython Jedi Temple after the Empire's Assault on Tython. Shortly thereafter, he was summoned to report to Darth Arkous regarding the Republic's Korriban Incursion and was reassigned to aid in reclaiming the Sith Academy on Korriban. During the battles on Korriban, he encountered a group of captured Sith apprentices and consulted with the Imperial strike team about whether to simply free them or compel them to fight and die for the Empire.
Arkous was ultimately killed on Rakata Prime while preparing Revan's Infinite Army, with some sources suggesting Lana Beniko's involvement. Tarsten quickly accepted this claim and condemned her for thwarting Revan's agenda. Eventually, Tarsten relocated to Rishi, a gathering place for many Revanites, and began serving Sith Lord Ivress. Arkous's killer eventually discovered their location and manipulated Tarsten and Ivress into suspecting Republic Captain Milenec of treachery, which ultimately contributed to the exposure of Revan's schemes on Rishi.