Robert Lyle Knepper (born July 8, 1959) is an American actor best known for his role as Theodore "T-Bag" Bagwell in the FOX drama series Prison Break from 2005 to 2009 and has also appeared in films such as Good Night, and Good Luck, Hitman and Transporter 3. Knepper joined the cast of Heroes in 2009 for its final season as Samuel Sullivan, and he played Sid Rothman in the neo-noir television series Mob City in 2013.