In 1998 he had recurring roles in the TV series Maximum Bob and Trinity. From 2001 to 2002 Trammell starred as Kevin “Space” Lauglin in the TV series Going to California. His best known role has come starring as Sam Merlotte in the TV series True Blood since 2008. Trammell has also starred in the films Wrestling with Alligators, Beat, Fear of Fiction, Autumn in New York, Followers, Undermind, Aliens vs. Predator: Requiem, The Details, Guns, Girls and Gambling, Crazy Kind of Love, The Privileged, White Rabbit, Things People Do, The Fault in Our Stars, and Me. He won a Satellite Award in 2009 and was nominated for a Screen Actors Guild Award in 2010.