Cecil B. Demented is a 2000 black comedy film written and directed by John Waters. The film stars Melanie Griffith as a snobby A-list Hollywood actress who is kidnapped by a band of terrorist filmmakers; they force her to star in their underground film. Stephen Dorff stars as the eponymous character and leader of the group, with Alicia Witt, Adrian Grenier, Maggie Gyllenhaal, and Michael Shannon co-starring as the rest of his gang of filmmakers.

The film, whose title (also the name of Dorff's character) alludes to director Cecil B. DeMille, is loosely based on the 1974 kidnapping of Patricia Hearst, who has a cameo role. Like all of Waters' films, it was shot in Baltimore, Maryland. The film was given a limited theatrical release in the United States on August 11, 2000, by Artisan Entertainment.