The Ninth Gate is a 1999 neo-noir horror thriller film directed, produced, and co-written by Roman Polanski. An international co-production between the United States, Portugal, France, and Spain, the film is loosely based upon Arturo Pérez-Reverte's 1993 novel The Club Dumas. The film stars Johnny Depp as a dealer of rare books who is tasked with authenticating a 17th-century book that, if used correctly, can summon the Devil.

The premiere showing was at San Sebastián, Spain, on 25 August 1999, a month before the 47th San Sebastian International Film Festival. Though critically and commercially unsuccessful in North America, where reviewers compared it unfavorably with Polanski's supernatural film Rosemary's Baby (1968), The Ninth Gate earned a worldwide gross of $58.4 million against a $38 million budget. It has since been described as a cult classic.