Dennis Carl Wilson (December 4, 1944 – December 28, 1983) was an American musician who co-founded the Beach Boys. He is best remembered as their drummer and as the middle brother of bandmates Brian and Carl Wilson. Dennis was the only true surfer in the Beach Boys, and his personal life exemplified the "California Myth" that the band's early songs often celebrated. He was also known for his association with the Manson Family and for co-starring in the 1971 film Two-Lane Blacktop.

Wilson served mainly on drums and backing vocals for the Beach Boys. His playing can be heard on many of the group's hits, belying the popular misconception that he was always replaced on record by studio musicians. He originally had few lead vocals on the band's songs, but his prominence as a singer-songwriter increased following their 1968 album Friends. His music is characterized for reflecting his "edginess" and "little of his happy charm". His original songs for the group included "Little Bird" (1968) and "Forever" (1970). Friends and biographers have asserted that he was an uncredited writer on "You Are So Beautiful", a 1974 hit for Joe Cocker frequently performed by Wilson in concert.

During his final years, Wilson struggled with alcoholism and the comorbid use of other drugs (including cocaine and heroin), exacerbating longstanding tensions with some of his bandmates. His solo album, Pacific Ocean Blue (1977), was released to warm reviews and moderate sales comparable to those of contemporaneous Beach Boys albums. Sessions for a follow-up, Bambu, disintegrated before his death. In 1983, Wilson drowned at age 39. In 1988, he was posthumously inducted into the Rock and Roll Hall of Fame as a member of the Beach Boys.