10 Actors Who Made Sure They Weren't Seen In TV Shows

George Clooney was a vocal early supporter of South Park, even reportedly mailing out around 500 VHS copies of Matt Stone and Trey Parker's prototype short film compilation "The Spirit of Christmas," which helped the pair gain esteem in Hollywood and eventually bring their vision to series.

The duo repaid Clooney by inviting him to provide a voiceover for the show's fourth ever episode, "Big Gay Al's Big Gay Boat Ride." Clooney voiced Sparky, Big Gay Al's gay dog, but the character didn't have any lines of dialogue - only barks.

Stone and Parker loved the idea of hiring an A-list actor to give such a minor performance, in stark contrast to The Simpsons' tendency for more feted front-and-center celebrity cameos.

Evidently Clooney was up for the deceptive cameo, the result of which left Comedy Central executives disappointed after expecting a far more overt voiceover performance from the actor.

Clooney did however memorably return to voice a doctor in 1999's movie adaptation, South Park: Bigger, Longer & Uncut.