- His first play, Killer Joe, premiered in a 40-seat theatre outside Chicago before eventually transferring to an off-Broadway theatre and London's West End.
- Joined the Steppenwolf Theatre Company's acting ensemble in 2002.
- Won the 2008 Pulitzer Prize for Drama for his play August: Osage County.
- Father Dennis Letts originated the role of August: Osage County patriarch Beverly Weston.
- The only person to have won a Tony Award for acting and a Pulitzer Prize.