Pet Sounds is the eleventh studio album by the American rock band the Beach Boys, released on May 16, 1966, by Capitol Records. It was initially met with a lukewarm critical and commercial response in the United States, peaking at number 10 on the Billboard Top LPs chart. In the United Kingdom, however, the album was lauded by critics and reached number 2 on the Record Retailer chart, remaining in the top ten for six months. Promoted there as "the most progressive pop album ever", Pet Sounds was recognized for its ambitious production, sophisticated music, and emotional lyrics. It is now considered to be among the greatest and most influential albums in music history.

The album was produced, arranged, and almost entirely composed by Brian Wilson with guest lyricist Tony Asher. It was recorded largely between January and April 1966, a year after Wilson had quit touring with his bandmates and debuted a more progressive sound with The Beach Boys Today! (1965). Wilson viewed Pet Sounds as effectively a solo album and credited part of its inspiration to marijuana and a newfound spiritual enlightenment. Galvanized by the work of his idol Phil Spector and rival group the Beatles, his goal was to create "the greatest rock album ever made", one without filler. An early concept album, it consists mainly of introspective and semi-autobiographical songs like "You Still Believe in Me", about a lover's unwavering loyalty; "I Know There's an Answer", a critique of LSD users; and "I Just Wasn't Made for These Times", about social alienation.

Incorporating elements of pop, jazz, exotica, classical, and the avant-garde, Wilson's Wall of Sound–based orchestrations mixed conventional rock set-ups with elaborate layers of vocal harmonies, found sounds, and instruments rarely if ever associated with rock, such as bicycle bells, French horn, flutes, Electro-Theremin, string sections, and soda cans. It marked the most complex instrumental and vocal parts of any Beach Boys album, and the first in which studio musicians (such as the Wrecking Crew) replaced the band on most of the instrumental tracks. The album could not be reproduced live and was the first time that any group had departed from their usual small-ensemble pop/rock band format for a whole LP. Its unprecedented total production cost exceeded $70,000 (equivalent to $660,000 in 2023). Lead single "Caroline, No" was issued as Wilson's official solo debut. It was followed by two singles credited to the group: "Sloop John B" and "Wouldn't It Be Nice" (backed with "God Only Knows"). A planned successor album, Smile, was never finished.

Pet Sounds revolutionized music production and the role of professional record producers, especially through Wilson's pioneering studio-as-instrument praxis. The record contributed to the cultural legitimization of popular music, a greater public appreciation for albums, the popularity of synthesizers, and the development of psychedelic music and progressive/art rock. It also introduced novel approaches to orchestration, chord voicings, and structural harmonies, such as its avoidance of definite key signatures. Although it had been widely revered by industry insiders, the album was obscure to mass audiences before being reissued in the 1990s, after which it topped several critics' and musicians' polls for the best album of all time, including those published by NME, Mojo, Uncut, and The Times. The album has also been consistently ranked number 2 in all editions of Rolling Stone's "The 500 Greatest Albums of All Time" list. As a solo artist, Wilson embarked on a string of Pet Sounds concert tours in the early 2000s and late 2010s. In 2004, the album was inducted into the National Recording Registry by the Library of Congress for being "culturally, historically, or aesthetically significant". Pet Sounds is certified platinum by the RIAA, indicating over one million units sold in the U.S. An expanded reissue, The Pet Sounds Sessions, was released in 1997, featuring the album's first true stereo mix.