Trout Mask Replica is the third studio album by the American band Captain Beefheart and his Magic Band, released as a double album on June 16, 1969, by Straight Records. The music was composed by Captain Beefheart (Don Van Vliet) and arranged by drummer John "Drumbo" French. Combining elements of R&B, garage rock, and blues with free jazz and avant-garde composition, the album is regarded as an important work of experimental rock. Its unconventional musical style, which includes polyrhythm, multi-octave vocals, and polytonality, has given the album a reputation as one of the most challenging recordings in the 20th century musical canon.

The album was produced by Frank Zappa and recorded in March 1969 at Whitney Studios in Glendale, California, following eight months of intense rehearsals at a small rented communal house in Los Angeles. The lineup of the Magic Band at this time consisted of Bill "Zoot Horn Rollo" Harkleroad and Jeff "Antennae Jimmy Semens" Cotton on guitar, Mark "Rockette Morton" Boston on bass guitar, Victor "The Mascara Snake" Hayden on bass clarinet, and John "Drumbo" French on drums and percussion. Beefheart played several brass and woodwind instruments, including saxophone, musette, and natural horn, and contributed most of the vocal parts, while Zappa and members of the band provided occasional vocals and narration. The well-rehearsed Magic Band recorded all instrumental tracks for the album in a single six-hour recording session; Beefheart's vocal and horn tracks were laid down over the next few days.

Trout Mask Replica sold poorly upon its initial release in the United States, where it failed to appear in any charts. It was more successful in the United Kingdom, where it spent a week at number 21 on the UK Albums Chart. In recent years, however, Trout Mask Replica has been widely regarded as the masterpiece of Beefheart's musical career, as well as an important influence on many subsequent artists. It was ranked number 60 on Rolling Stone's 2012 edition of the 500 Greatest Albums of All Time list, and has appeared on the "best of" lists of many other publications. In 2010, the album was selected for preservation in the United States National Recording Registry by the Library of Congress for being deemed "culturally, historically, or aesthetically significant".