Os Mutantes (Portuguese for The Mutants) was an influential band that arose out of Brazil's Tropicalia movement of the late 1960's. Even during a period of worldwide musical experimentation and exploration, Os Mutantes stood out as being inventive with their musical styles, spanning psychedelia, pop, blues, and rock genres. The group experimented with distortion, wordplay, feedback, and unusual instruments to create a free and playful pop sound. According to the liner notes of Everything is Possible, one of the main instruments on Le Premier Bonheur du Jour is an aerosol bugspray can.

Os mutantes was formed in Sao Paulo, Brazil in 1965 by brothers Arnaldo and Sergio Baptista along with their lead singer Rita Lee. They delivered five albums before Lee departed in 1972 to start her own solo career.

Though Os Mutantes did not spread into the popular commercial market, they did influence many English-speaking artists. For example, Kurt Cobain publicly requested a reunion tour from the trio in 1993, Beck released an experimental album called Mutations with the hit song Tropicalia, and David Byrne assembled Everything is Possible, the Os Mutantes' compilation album released by Luaka Bop in 1999.