15 Big Ones is the 20th studio album by the American rock band the Beach Boys, released July 5, 1976, by Brother/Reprise. It includes a mix of original songs and renditions of rock 'n' roll and R&B standards. The LP was the band's first album with production credited solely to Brian Wilson since Pet Sounds (1966). As such, its release was accompanied by a controversial media campaign that declared his comeback as an active member of the Beach Boys' recording and touring group.

Following their previous album, Holland (1973), the band had focused on touring and attracting bigger concert audiences, especially after the unexpected success of their greatest hits compilation Endless Summer (1974). They attempted to record a new album at Caribou Ranch studio in late 1974, but it was soon abandoned, partly due to Wilson being unable or unwilling to participate. At the end of 1975, his bandmates and manager Stephen Love prevailed upon him to produce the group's next release, hoping that a new album bearing his production label credit would prove lucrative.

Most of 15 Big Ones was hastily recorded in early 1976 at the band's Brother Studios. The project was marred by creative disputes, time constraints, health issues among the band members, and interference from Brian's psychologist, Eugene Landy. One of the proposed titles, Group Therapy, was rejected in favor of a title that referred to both the number of tracks and the group's 15th anniversary. To support the album, Brian joined his bandmates on a major concert tour for the first time since 1964. The group also commissioned an NBC television special, titled The Beach Boys, that aired in August.

Despite mixed reviews, 15 Big Ones was the Beach Boys' best-selling album of new material since 1965, earning a gold certification from the RIAA. It peaked at number 8 in the U.S. and number 31 in the UK. Three singles were issued: a cover of Chuck Berry's "Rock and Roll Music" (number 5) and the originals "It's OK" (number 29) and "Everyone's in Love with You". The former two were their only top 30 hits in this decade. Brian later referred to 15 Big Ones and its 1977 follow-up, The Beach Boys Love You, as his favorite and most artistically representative work.