Imagine is the second solo studio album by English musician John Lennon, released on 9 September 1971 by Apple Records. Co-produced by Lennon, his wife Yoko Ono and Phil Spector, the album's elaborate sound contrasts the basic, small-group arrangements of his first album, John Lennon/Plastic Ono Band (1970), while the opening title track is widely considered to be his signature song.

Lennon recorded the album from early to mid-1971 at his Ascot Sound Studios, EMI Recording Studios and the Record Plant in New York City, with supporting musicians that included his ex-Beatles bandmate George Harrison, keyboardist Nicky Hopkins, bassist Klaus Voormann and drummers Alan White and Jim Keltner. Its lyrics reflect peace, love, politics, Lennon's experience with primal scream therapy, and, following a period of high personal tensions, an attack on his former writing partner Paul McCartney in "How Do You Sleep?" Extensive footage from the sessions was recorded for a scrapped documentary; parts were released on the documentary film Imagine: John Lennon (1988). The documentary John & Yoko: Above Us Only Sky, based on that footage, was released in 2018.

Imagine was a critical and commercial success, peaking at number one on both the UK Albums Chart and US Billboard 200. Along with John Lennon/Plastic Ono Band, it is considered one of Lennon's finest solo albums. In 2012, the album was voted 80th on Rolling Stone magazine's list of the 500 Greatest Albums of All Time. The album has been reissued multiple times, including in 2018 as The Ultimate Collection, a six-disc box set containing previously unreleased demos, rare studio outtakes, "evolution documentaries" for each track, and isolated track elements along with surround mixes.