The new BBC drama focuses on a group of people who leave Earth to start a new life.
Mabius, who previously starred in Ugly Betty, has now explained that he likes the ambiguous nature of his character.
According to the Los Angeles Times, he said: "It's probably one of the most fun characters I've ever played because he's not black and white. He's sort of the hero and anti-hero in this new place."
Outcasts also stars Hermione Norris, Danny Mays, Jamie Bamber and Ashley Walters. It is expected to air on BBC One later this year.