The Decay of Fiction is a 2002 American 35mm part color and part black-and-white experimental film noir project directed by independent filmmaker and artist Pat O'Neill. The film, initially conceived as a documentary, was produced by O'Neill and Rebecca Hartzell for Lookout Mountain Films. Filming took place in Los Angeles.

The film is set at the site of the old Ambassador Hotel in Los Angeles. It has no identifiable plot and features no recurring characters. An estimated budget of $250,000 was put forth to fund the film and it took eight years to complete. It premiered on October 12, 2002, at the New York Film Festival. The film has also been screened at six other film festivals and at eight non-festival exhibitions. It received generally favorable reviews. Multiple critics commented on the film's visual appeal.