Alphaville: Une étrange aventure de Lemmy Caution (Alphaville: A Strange Adventure of Lemmy Caution) is a 1965 black-and-white French science fiction film directed by Jean-Luc Godard. It stars Eddie Constantine, Anna Karina, Howard Vernon and Akim Tamiroff. The film won the Golden Bear award of the 15th Berlin International Film Festival in 1965.

Alphaville combines the genres of dystopian science fiction and film noir. Although set far in the future on another planet, there are no special effects or elaborate sets; instead, the film was shot in real locations in Paris, the night-time streets of the capital becoming the streets of Alphaville, while modernist glass and concrete buildings (in 1965 they were new and strange architectural designs) represent the city's interiors. In addition, the characters refer to twentieth century events; for example, the hero describes himself as a Guadalcanal veteran.

Expatriate American actor Eddie Constantine plays Lemmy Caution, a trenchcoat-wearing secret agent. Constantine had already played this or similar roles in dozens of previous films; the character was originally created by British pulp novelist Peter Cheyney. However, in Alphaville, director Jean-Luc Godard moves Caution away from his usual twentieth century setting, and places him in a futuristic sci-fi dystopia, the technocratic dictatorship of Alphaville.