- Principal Slimovitz
- Slimovitz's Ancestor
Rash played Mr. Grayson/Stitches, a sidekick to the supervillain 'Royal Pain' in the 2005 film Sky High and as the recurring character Fenton on That '70s Show, and "Andrew the Whore House Guy" on Reno 911!. He also guest starred in the last episode of Friends, and played the role of Head T.A. Philip in Slackers. Since 2009, Rash has starred on Community as Dean Craig Pelton.
Rash and comedy partner Nat Faxon have recently moved into screenwriting. Their screenplay, based on Kaui Hart Hemmings' novel The Descendants, was on the 2008 edition of the Black List, a list of the most popular unproduced scripts in Hollywood. The film was produced in Hawaii, directed by Alexander Payne, starred George Clooney, and was released on November 18, 2011 to critical acclaim. Payne, Faxon and Rash received a Golden Globe nomination and won an Academy Award for Best Adapted Screenplay for their work.