12. Jimmy Fallon
Years on Show: 1998-2004
Most Memorable Sketches: "Weekend Update," "Jarret's Room," "The Barry Gibb Show," "I Wish It Was Christmas Today"
Post-Show Career: He had a brief run as an actor in failed movies like Taxi and Fever Pitch, but then he took over Late Night from Conan O'Brien and his career went into the stratosphere.