Here is a photo of Mos Def from Dexter Season 6, via EW: When the Showtime series returns this fall for a sixth season, there will be plenty of fresh blood, including Edward James Olmos, Colin Hanks, and Mos Def (right, with Michael C. Hall). The rapper-actor plays Brother Sam, a reformed criminal who runs an auto-body shop. He crosses paths with our resident serial killer when one of his employees comes under investigation. Says executive producer Scott Buck, ''Dexter is unconvinced that Brother Sam is a man who found God and changed his violent ways".