South Park: Bigger, Longer & Uncut is a 1999 American adult animated musical comedy film based on the animated sitcom South Park. The film was directed by series creator Trey Parker from a screenplay co-written with series co-creator Matt Stone and Pam Brady; and stars Parker, Stone, Mary Kay Bergman, and Isaac Hayes, all of whom reprise their roles from the series, with George Clooney, Eric Idle, and Mike Judge in supporting roles. The plot follows Stan, Kyle, Cartman, and Kenny as they sneak into an R-rated film starring the Canadian comedy duo Terrance and Phillip, after which they begin swearing. When the consequent moral panic culminates in the United States declaring war on Canada, Stan, Kyle and Cartman take it upon themselves to save Terrance and Phillip from execution, while Kenny tries to prevent a prophecy involving Satan and Saddam Hussein's intent to conquer the world.

Primarily centered on themes of censorship and scapegoating, the film also parodies and satirizes the animated films of the Disney Renaissance, musicals such as Les Misérables, and controversies surrounding the series itself. The film also heavily satirizes the Motion Picture Association of America; during production, Parker and Stone disputed with the MPAA, which returned the film multiple times with an NC-17 rating due to its frequent use of profanity. The film's songs were written by Parker and Marc Shaiman, the latter of whom composed the score.

South Park: Bigger, Longer & Uncut premiered at Grauman's Chinese Theater on June 23, 1999, and was released theatrically in the US and Canada the following week by Paramount Pictures, with Warner Bros. handling international distribution. The film received generally positive reviews from critics, who praised its story, soundtrack, humor and themes. Produced on a $21 million budget, it grossed $83.1 million worldwide, making it the highest-grossing R-rated animated film until 2016. At the 72nd Academy Awards, the song "Blame Canada" was nominated for Best Original Song, but lost to Phil Collins' "You'll Be in My Heart" from Tarzan.