Born in 1812 London, he would suffer his first death in the year 1843, when he was shot while robbing a manor house. He was found by Christopher Claremont who told him about his Immortality. Tarsis remained a crook, and by the beginning of the 20th century, he started to expand into bigger jobs, than just house breaking.
In 1913 he found his future partner in crime, Lucas Kagan. While visiting Ireland, Tarsis found a young boy dealing with some bullies, Tarsis sensed that Kagan was a pre-Immortal. Kagan lived on the streets and fended for himself. Tarsis appreciated his toughness, and over the years, he become a mentor to Lucas and schooled him in the life of crime.
In 1923, after Tarsis and Kagan robbed a bank, Tarsis decided Kagan was at his physical peak, and shot him to death in order to trigger his Immortality.
In 1930, while in Paris, Tarsis and Kagan robbed a bank where they sensed the presence of another Immortal, it was Duncan MacLeod, who was making a transaction there. Duncan told Tarsis that what they did was none of his business unless someone got hurt. When Tarsis and Kagan left, however, they fired their tommyguns with abandon, and killed a bystander.
That night, Tarsis and Kagan were at a bordello when MacLeod arrived to challenge Tarsis. Duncan defeated Tarsis and beheaded him and received his Quickening.