Feel free to add your own
  1. Voicing a recurring character on "The Cleveland Show"- Kanye West
    His name was Kenny West
  2. Featuring in "Austin Powers"- Beyonce
    She was in a ~sequel~
  3. Inexplicably writing a small chapter in blackface- David Foster Wallace, Infinite Jest
    "Wardine be cry." Yikes.
  4. Coen brothers - remaking the Alec Guinness pitch perfect Ladykillers as a studio movie
    And to be clear, I am an ardent fan, and lay blame on someone nameless at the studio
    Suggested by @gilbaron
  5. Garfield- Bill Murray
    (And Garfield 2, Ben points out)