After South Park made its television debut back in August 1997, it quickly earned itself some high-profile fans. However, only a select few have ended up making guest appearances on the long-running animated series. Some, like Jennifer Aniston and Richard Belzer, got the opportunity to voice random characters early in the show’s run. Others lucked out and got to play versions of themselves, including entire bands like Korn and Radiohead.

Even more celebrities expressed interest in being on South Park, but nothing ever came of it, for whatever reason. Tiger Woods, for example, offered to lend his voice to an episode at one point. Surprisingly, Tom Cruise and Steven Spielberg were also looking to get involved in some way, shape, or form back then. As fate would have it, Woods, Cruise, and Spielberg would all be targeted by the show during its later seasons.

Why Jerry Seinfeld Backed Out of ‘South Park’ After Pushing to Join the Show

And on at least one occasion, a celebrity fan turned down an invitation from Trey Parker and Matt Stone to voice a South Park character despite having reached out to them in the first place. While the series was still in its first season, Parker and Stone received a call from Jerry Seinfeld’s manager, telling them how much Seinfeld loved South Park and wanted to collaborate with them. The idea started to sound much less appealing when the show’s creators offered Seinfeld the role of one of the many turkeys featured in their 1997 Thanksgiving episode “Starvin’ Marvin.” “The manager said, ‘This is Jerry Seinfeld. Call us back when you have something bigger,” Parker told Rolling Stone around that time. 

Needless to say, Seinfeld never made an appearance, but several other stars were cool with providing their own animal noises at Parker and Stone’s request. George Clooney, for one, did the barking for Stan’s dog, Sparky, in the Season 1 episode “Big Gay Al’s Big Gay Boat Ride”:

And those meows you hear coming out of Cartman’s cat, Mr. Kitty, in “Cartman’s Mom is a Dirty Slut” were brought to us courtesy of former Tonight Show host Jay Leno:

Happy Days star Henry Winkler got thrown in the mix as well when he provided the unforgettable sounds of the big black scary monster in the following season’s “City on the Edge of Forever.” You can check out Winkler’s brief contribution to the series below.