Copkiller (Italian: Copkiller (L'assassino dei poliziotti)), also released as Corrupt, Corrupt Lieutenant, and The Order of Death, is a 1983 Italian crime thriller film directed by Roberto Faenza and starring Harvey Keitel and John Lydon, the lead singer for the bands Sex Pistols and Public Image Ltd. It is based on Hugh Fleetwood's 1977 novel The Order of Death, with a screenplay by Fleetwood, Faenza and Ennio De Concini. The music was composed by Ennio Morricone. The plot follows a psychological cat-and-mouse game between a corrupt police officer (Keitel) and a disturbed young man (Lydon) against the backdrop of murders committed by a serial killer who is targeting police officers.

The film was shot on-location in New York City and at Cinecittà Studios in Rome between March and April, 1982. It is Lydon's only starring role in film to date. Upon release, it received mixed-to-negative reviews from critics, and has since fallen into the public domain. It has since undergone a reevaluation, and has become a cult classic due to the presence of Keitel and Lydon, while being acknowledged as a precursor to Abel Ferrara's celebrated and similarly-themed film Bad Lieutenant (1992).