"Theme for an Imaginary Western" is a song written by Jack Bruce and Pete Brown. The song is sometimes referred to as "Theme from an Imaginary Western." It has been performed by many artists, including Mountain, Jack Bruce, Leslie West, Colosseum, Greenslade, DC3 and Johan Asherton. In 1988, Bruce teamed up with Mountain guitarist Leslie West, and performed the song again on West's Theme album, which was named after the song. West also performed it on Leslie West Live!. The song is a standard on Colosseum gigs and it is also recorded on Daughter of Time (1970) and Colosseum Live05 (2007).