"Space Oddity" is a song by English singer-songwriter David Bowie. It was first released on 11 July 1969 by Philips Records as a 7-inch single, then as the opening track of his second studio album David Bowie. Produced by Gus Dudgeon and recorded at Trident Studios in London, it is a tale about a fictional astronaut named Major Tom; its title and subject matter were partly inspired by 2001: A Space Odyssey (1968) and Bowie's feelings of alienation at that point in his career. One of the most musically complex songs he had written up to that point, it represented a change from the music hall-influenced sound of his debut to a sound akin to psychedelic folk and inspired by the Bee Gees.

Rush-released as a single to capitalise on the Apollo 11 Moon landing, it received critical praise and was used by the BBC as background music during its coverage of the event. It initially sold poorly but soon reached number five in the UK, becoming Bowie's first and only chart hit for another three years. A 1972 reissue by RCA Records was Bowie's first US hit and was promoted with a new music video filmed by Mick Rock. Another 1975 reissue as part of a maxi-single became Bowie's first UK number-one single. Bowie re-recorded an acoustic version in 1979. A mainstay during Bowie's concerts, Bowie revisited the Major Tom character in his later singles, notably the sequel song "Ashes to Ashes" (1980).

A range of artists have covered "Space Oddity" and others have released songs that reference Major Tom. A 2013 cover by Canadian astronaut Chris Hadfield gained widespread attention; its music video was the first filmed in space. The song has appeared in numerous films and television series, and has a pivotal role in the 2013 film The Secret Life of Walter Mitty. In 2019, Visconti remixed Bowie's original recording to mark the 50th anniversary of its first release, with a new music video directed by Tim Pope. Initially viewed as a novelty track, "Space Oddity" is now considered one of Bowie's finest recordings and remains one of his most popular songs. It has appeared in numerous "best-of" lists, including the Rock and Roll Hall of Fame's "500 Songs that Shaped Rock and Roll".