Smiley Smile is the twelfth studio album by the American rock band the Beach Boys, released on September 18, 1967. Conceived as a simpler and more relaxed version of their unfinished Smile album, Smiley Smile is distinguished for its homespun arrangements, "stoned" aesthetic, and lo-fi production. Critics and fans generally received the album and its lead single, "Heroes and Villains", with confusion and disappointment. The album reached number 9 on UK record charts, but sold poorly in the U.S., peaking at number 41—the band's lowest chart placement to that point.

Following principal songwriter Brian Wilson's declaration that most of the original Smile tapes would be abandoned, the majority of the recording sessions lasted for six weeks at his makeshift home studio using radio broadcasting equipment, a detuned piano, electronic bass, melodica, found objects for percussion, and a Baldwin theater organ. The unconventional recording process juxtaposed an experimental party-like atmosphere with short pieces of music edited together in a disjointed manner, combining the engineering methods of "Good Vibrations" (1966) with the loose feeling of Beach Boys' Party! (1965). Despite leading these sessions, Wilson deliberately credited the album's production to the group collectively for the first time.

From late 1966 to mid-1967, Smile had been repeatedly delayed while the Beach Boys were subject to a considerable level of media hype proclaiming Wilson to be a "genius". After settling payment disputes with Capitol Records, Smiley Smile was distributed in collaboration with Brother Records, the band's new self-owned record company. A second single, "Gettin' Hungry", was credited to Wilson and Mike Love and failed to chart. Smile was left incomplete as the band immediately moved onto the recording of Lei'd in Hawaii, an unfinished live album featuring performances in the style of Smiley Smile, and Wild Honey, released in December 1967.

Smiley Smile has since become a critical and cult favorite, influencing the development of the lo-fi, ambient, and bedroom pop genres. It is often regarded as one of the finest chill-out albums for having positive effects on listeners experiencing an LSD comedown, a usage adopted by at least one drug clinic. In 1974, it was ranked number 64 in NME's list of the greatest albums of all time. Outtakes and session highlights from the album were included on the compilations The Smile Sessions (2011) and 1967 – Sunshine Tomorrow (2017).