"Life on Mars?" is a song by the English singer-songwriter David Bowie, first released on his 1971 album Hunky Dory. Bowie wrote the song as a parody of Frank Sinatra's "My Way". "Life on Mars?" was recorded on 6 August 1971 at Trident Studios in London, and was co-produced by Bowie and Ken Scott. Bowie's backing band consisted of guitarist and string arranger Mick Ronson, bassist Trevor Bolder, drummer Mick Woodmansey and Strawbs member Rick Wakeman on piano. "Life on Mars?" is primarily a glam rock ballad, with elements of cabaret and art rock; it has a complex structure that includes chord changes throughout. The lyrics are about a girl who goes to a cinema to escape reality, and include surreal images that reflect optimism and the effects of Hollywood.

At the height of Bowie's fame as Ziggy Stardust, RCA Records issued "Life on Mars?" as a single on 22 June 1973 in the United Kingdom, where it peaked at number three. To promote the single, photographer Mick Rock filmed a video that shows Bowie in make-up and a turquoise suit singing the song against a white backdrop. Bowie frequently performed "Life on Mars?" during his concerts and the song has appeared on numerous compilation albums. Scott remixed the song in 2003 and 2016, the latter being a "stripped down" mix.

"Life on Mars?" is considered by commentators as one of Bowie's greatest songs, and of the best songs of all time. Critics have praised Bowie's vocal performance and growth as a songwriter. The song's title was given to the British television series Life on Mars, and films and other television programmes have included "Life on Mars?". Artists including Barbra Streisand, and Nine Inch Nails members Trent Reznor and Atticus Ross, have recorded cover versions of the song; and following the David Bowie's death in 2016, "Life on Mars?" was frequently chosen as a tribute to the artist.