Psycho is a 1960 American psychological horror thriller film produced and directed by Alfred Hitchcock. The screenplay, written by Joseph Stefano, was based on the 1959 novel of the same name by Robert Bloch. The film stars Anthony Perkins, Janet Leigh, Vera Miles, John Gavin and Martin Balsam, and centers on the encounter between a female embezzler on the run, Marion Crane (Leigh), and Norman Bates (Perkins), the shy proprietor of a secluded old motel, and its aftermath.

Psycho was seen as a departure from Hitchcock's previous film North by Northwest, as it was filmed on a lower budget in black-and-white with crew members from his television series Alfred Hitchcock Presents. The film was initially considered controversial and received mixed reviews, but audience interest and outstanding box-office returns prompted a major critical re-evaluation. Psycho was nominated for four Academy Awards, including Best Supporting Actress for Leigh and Best Director for Hitchcock.

Psycho is now considered one of Hitchcock's best films and praised as a major work of cinematic art by international film critics and scholars due to its slick direction, tense atmosphere, effective camerawork, a memorable score and iconic performances. Often ranked among the greatest films of all time, it set a new level of acceptability for violence, deviant behavior and sexuality in American films,and is widely considered to be the earliest example of the slasher film genre.

After Hitchcock's death in 1980, Universal Pictures began producing follow-ups: three sequels, a remake, a made-for-television spin-off, and a prequel television series set in the 2010s. In 1992, the Library of Congress deemed the film "culturally, historically, or aesthetically significant" and selected it for preservation in the National Film Registry.