Film noir (; French: [film nwaʁ]) is a cinematic term used primarily to describe stylish Hollywood crime dramas, particularly those that emphasize cynical attitudes and motivations. The 1940s and 1950s are generally regarded as the "classic period" of American film noir. Film noir of this era is associated with a low-key, black-and-white visual style that has roots in German Expressionist cinematography. Many of the prototypical stories and much of the attitude of classic noir derive from the hardboiled school of crime fiction that emerged in the United States during the Great Depression.

The term film noir, French for 'black film' (literal) or 'dark film' (closer meaning), was first applied to Hollywood films by French critic Nino Frank in 1946, but was unrecognized by most American film industry professionals of that era. Frank is believed to have been inspired by the French literary publishing imprint Série noire, founded in 1945.

Cinema historians and critics defined the category retrospectively. Before the notion was widely adopted in the 1970s, many of the classic films noir were referred to as "melodramas". Whether film noir qualifies as a distinct genre or whether it is more of a filmmaking style is a matter of ongoing and heavy debate among scholars.

Film noir encompasses a range of plots: the central figure may be a private investigator (The Big Sleep), a plainclothes police officer (The Big Heat), an aging boxer (The Set-Up), a hapless grifter (Night and the City), a law-abiding citizen lured into a life of crime (Gun Crazy), or simply a victim of circumstance (D.O.A.). Although film noir was originally associated with American productions, the term has been used to describe films from around the world. Many films released from the 1960s onward share attributes with films noir of the classical period, and often treat its conventions self-referentially. Some refer to such latter-day works as neo-noir. The clichés of film noir have inspired parody since the mid-1940s.