2001: A Space Odyssey is a 1968 epic science fiction film produced and directed by Stanley Kubrick. The screenplay was written by Kubrick and Arthur C. Clarke. Its plot was inspired by several short stories optioned from Clarke, primarily "The Sentinel" (1951) and "Encounter in the Dawn" (1953). The film stars Keir Dullea, Gary Lockwood, William Sylvester, and Douglas Rain. It follows a voyage by astronauts, scientists, and the sentient supercomputer HAL 9000 to Jupiter to investigate an alien monolith.

The film is noted for its scientifically accurate depiction of spaceflight, pioneering special effects, and ambiguous themes. Kubrick avoided conventional cinematic and narrative techniques; dialogue is used sparingly, and there are long sequences accompanied only by music. Shunning the convention that major film productions should feature original music, 2001: A Space Odyssey takes for its soundtrack numerous works of classical music, including pieces by Richard Strauss, Johann Strauss II, Aram Khachaturian, and György Ligeti.

Polarising critics after its release, 2001: A Space Odyssey has since been subject to a variety of interpretations, ranging from the darkly apocalyptic to an optimistic reappraisal of the hopes of humanity. Critics noted its exploration of themes such as human evolution, technology, artificial intelligence, and the possibility of extraterrestrial life. It was nominated for four Academy Awards, winning Kubrick the award for his direction of the visual effects, which apart from his lifetime-achievement Oscar, was the only Academy Award the director would receive.

The film is now widely regarded as one of the greatest and most influential films ever made. In 1991, it was selected by the United States Library of Congress for preservation in the National Film Registry. In 2022, 2001: A Space Odyssey placed in the top ten of Sight & Sound's decennial critics' poll, and topped their directors' poll. A sequel, 2010: The Year We Make Contact, was released in 1984, based on the novel 2010: Odyssey Two. Clarke published a novelisation of 2001 (in part written concurrently with the screenplay) soon after the film's 1968 release, for which Kubrick received co-writing credit.