Tracy S. Letts (born July 4, 1965) is an American actor, playwright, and screenwriter. He started his career at the Steppenwolf Theatre before making his Broadway debut as a playwright for August: Osage County (2007), for which he received the Pulitzer Prize for Drama and the Tony Award for Best Play. As an actor, he won the Tony Award for Best Actor in a Play for the Broadway revival of Who's Afraid of Virginia Woolf? (2013).

As a playwright, Letts is known for having written for the Steppenwolf Theatre, Off-Broadway and Broadway theatre. His works include Killer Joe, Bug, Man from Nebraska, August: Osage County, Superior Donuts, Linda Vista, and The Minutes. Letts adapted three of his plays into films, Bug and Killer Joe, both directed by William Friedkin, and August: Osage County, directed by John Wells. His 2009 play Superior Donuts was adapted into a television series of the same name. As a stage actor, Letts has performed in various classic plays with the Steppenwolf Theatre since 1988. He made his acting Broadway debut as George in the revival of Edward Albee's play Who's Afraid of Virginia Woolf?, which earned him a Tony Award for Best Actor in a Play. He continued acting on the Broadway stage in The Realistic Joneses, All My Sons, and The Minutes.