Z Channel: A Magnificent Obsession is a 2004 documentary film about Los Angeles pay cable channel Z Channel which was directed by Xan Cassavetes, daughter of Hollywood director and actor John Cassavetes. It was screened out of competition at the 2004 Cannes Film Festival.

The documentary is about Z Channel, which was one of the early pay cable TV stations in the United States. Z Channel became famous for showing an eclectic variety of films, including foreign language, silent, documentary, director's cut, forgotten, overlooked, under-appreciated, erotic as well as mainstream films, without commercials and uncut and letterboxed when possible.

The film also tells the story of Z Channel's programming director Jerry Harvey who was a film lover, programming genius, and a man almost single-handedly responsible for getting many great films shown to the public. It gives insights into Harvey's constant battle with personal demons, which resulted in him ending his life and the life of his wife in a murder-suicide.

Throughout the film a variety of footage featuring some of the films shown on the Z Channel is used. This serves to underline the diversity offered on the channel in particular its attempts to expose its American viewers to undubbed foreign language films.

The films ends with a montage of scenes of such films with Irving Berlin's "What'll I Do?" theme being played over the top of them as performed by the actor William Atherton from the film The Great Gatsby (1974).