Ever watch a movie and swear you recognize a voice, but you just can't place it? That’s basically the entire experience of watching South Park: Bigger, Longer & Uncut. Most people assume it’s just Trey Parker and Matt Stone doing every single voice in a basement.
They do a lot. Like, a lot lot.
But the 1999 theatrical masterpiece actually featured a wild mix of A-list celebrities, Broadway-caliber singers, and British comedy royalty. Some of these people were so famous they didn't even want their real names in the credits. Others were there because Trey and Matt just thought it would be funny to give a megastar the most pathetic role possible.
The South Park movie cast is a weird time capsule of late-90s Hollywood. It’s also one of the few times we got to hear some of these legendary voices before they left the show—or the world—forever.
The Two-Man Army: Parker and Stone
You’ve gotta start with the creators. Honestly, the sheer volume of characters these two voice is exhausting just to look at.
Trey Parker is the musical backbone. He’s Stan Marsh and Eric Cartman, obviously. But in the movie, he also took on the flamboyant singing voice of Big Gay Al (though Matt did the speaking parts) and the terrifying, surprisingly vulnerable voice of Satan. If you listen closely to the "The Mole" (Christophe), that’s Trey too, doing a very specific French accent that he somehow makes sound cool and annoying at the same time.
Matt Stone covers the rest of the core four. He’s Kyle Broflovski and the muffled, parka-wearing Kenny McCormick. But his biggest contribution to the movie’s lore? Saddam Hussein. Fun fact: Saddam is actually credited as "Himself" in the movie. It’s not actually the late dictator, of course. It’s Matt Stone doing a high-pitched, whiny voice that makes the Butcher of Baghdad look like a codependent boyfriend.
He also handles Terrance (of Terrance and Phillip), while Trey handles Phillip. They basically split the world between them.
The Legendary Mary Kay Bergman
We have to talk about Mary Kay Bergman. She was the "female voice" of South Park during its explosive first few years. In the movie, she voiced almost every woman in town: Wendy Testaburger, Sheila Broflovski, Sharon Marsh, and Liane Cartman.
She even voiced "The Clitoris." Yes, really.
Bergman was a titan in the voice acting world. You might know her as Daphne from Scooby-Doo or various voices in Disney’s Hercules and Mulan. Sadly, she passed away shortly after the movie’s release. The show was never quite the same without her specific brand of "angry suburban mom" energy. When people talk about the South Park movie cast, they often overlook how much heavy lifting she did to make the musical numbers like "Blame Canada" actually sound professional.
Isaac Hayes and the Soul of Chef
Isaac Hayes brought a level of "cool" to the movie that Trey and Matt simply couldn't manufacture. As Chef, Hayes was the only adult the kids actually trusted. His performance in the movie is peak Chef. He gets the big "Chocolate Salty Balls" energy (though that was a TV hit, his movie presence is just as smooth).
The movie was made during the height of Hayes' popularity on the show. It was years before the infamous Scientology fallout that led to his departure. In Bigger, Longer & Uncut, you can hear the genuine chemistry he had with the creators. He wasn't just a voice actor; he was a funk legend giving the movie its heart.
George Clooney: The Doctor Who Killed Kenny
This is the one most people get wrong or just flat-out miss. George Clooney is in the South Park movie.
But he’s not a main character.
Clooney was a massive fan of the "Spirit of Christmas" short that went viral before the show even existed. He actually helped spread the tape around Hollywood. To thank him, Trey and Matt gave him a role in the TV show... as Stan's gay dog, Sparky. He just barked.
For the movie, they gave him a "promotion." He voices Dr. Gouache, the ER doctor who tries to save Kenny after he lights himself on fire. Clooney delivers the lines with total seriousness before inadvertently replacing Kenny's heart with a baked potato. The potato explodes. The doctor shrugs and walks away whistling. It’s peak Clooney, honestly.
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The British Invasion: Eric Idle and Mike Judge
If you grew up on Monty Python, you definitely recognized the voice of Dr. Vosknocker. That’s Eric Idle. He plays the "swearing expert" brought in to implant the V-chip into Cartman’s brain. It’s a perfect bit of casting because South Park owes its entire existence to the surrealist humor of the Python crew.
Then there’s the ending. The moment everyone waited for.
For the first time ever, Kenny McCormick takes off his hood. He speaks. He doesn't sound like Matt Stone’s muffled mumbles. He sounds like a real kid. That voice? It’s Mike Judge, the creator of Beavis and Butt-Head and King of the Hill.
It’s a tiny, one-line cameo ("Goodbye, you guys"), but it was a massive "clash of the titans" moment for 90s animation fans.
A Quick Look at the Cameo Chaos
The credits for this movie are a "who's who" of people who were just happy to be there.
- Minnie Driver: She voices Brooke Shields. It’s a brief, hilarious parody that Driver leans into completely.
- Dave Foley: The Kids in the Hall star shows up as the Baldwin brothers' assistant (or rather, just another Canadian caught in the crossfire).
- Brent Spiner: Data from Star Trek? Yeah, he’s in there voicing Conan O’Brien.
- Nick Rhodes: The keyboardist from Duran Duran plays a Canadian fighter pilot. Why? Because why not.
Why the Cast Worked So Well
The South Park movie cast succeeded because it didn't rely on celebrity "stunt casting" to sell tickets. In most animated movies, the celebrities are the selling point. In South Park, the celebrities are the joke.
Trey and Matt didn't want the audience to point at the screen and say, "Look, it's George Clooney!" They wanted you to laugh at the absurdity of a world-famous actor playing a negligent doctor. They treated their guest stars like props.
This approach allowed the movie to keep its "indie" feel despite being a multi-million dollar Paramount production. It kept the focus on the four boys, the music, and the scathing satire of censorship and parenting.
What to Watch for Next Time
If you're planning a re-watch, keep your ears open for these specific moments that define the South Park movie cast experience:
- The "La Resistance" Medley: Listen to the layers of voices. This is where you can really hear the difference between the "character" voices (Stan/Kyle) and the professional Broadway backing that Marc Shaiman brought in.
- The Saddam/Satan Scenes: Pay attention to the vocal range Matt Stone uses for Saddam. It’s a masterclass in being intentionally annoying.
- The Doctor Scene: Now that you know it’s Clooney, the "baked potato" line hits different. He’s using his "serious actor" voice for the dumbest dialogue ever written.
- The Ending: Don't blink, or you'll miss the Mike Judge cameo. It's the only time in the entire franchise history that Kenny sounds like a normal human being.
Instead of just looking at the IMDb list, try to spot the subtle shifts in tone when a guest star takes over. The movie is a rare example of a "cult" cast that actually delivered a mainstream masterpiece. Check out the 25th-anniversary materials or the "Making of" documentaries if you want to see just how chaotic those recording sessions actually were.