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 for its fourth and final season as Samuel Sullivan from 2009 to 2010, and he played Sid Rothman in the neo-noir television series Mob City in 2013. He will star as Antonius in The Hunger Games: Mockingjay – Part 1 and Part 2. He will appear with an ensemble cast in the mini-series Texas Rising in 2015.
Born in Fremont, Ohio, Knepper was interested in acting from an early age due to his mother's involvement at a community theater. He was raised in Maumee, Ohio, near Toledo, by his mother and father, who were veterinarians. Knepper spent many years of his youth working in the community theater and high school productions. After graduating from Maumee High School in 1977, he attended Northwestern University to study drama. During this time, Knepper also obtained professional roles in plays in Chicago. Nearing the completion of his degree, Knepper quit Northwestern and went to New York City, where he continued to work in theater.
Although Knepper never intended to work in film and television projects, he began his television and film career in 1986 with The Paper Chase and That's Life!. Knepper went on to have larger roles in such films as Wild Thing, Young Guns II, When the Bough Breaks and Everyone Says I Love You. He also made appearances on well known television series such as The Twilight Zone, Star Trek: The Next Generation, ER and Law & Order. Through this time Knepper still continued to do theatre work.