The Byrds () were an American rock band formed in Los Angeles, California, in 1964. The band underwent multiple lineup changes throughout its existence, with frontman Roger McGuinn (known as Jim McGuinn until mid-1967) remaining the sole consistent member. Although their time as one of the most popular groups in the world only lasted for a short period in the mid-1960s, the Byrds are today considered by critics to be among the most influential rock acts of their era. Their signature blend of clear harmony singing and McGuinn's jangly 12-string Rickenbacker guitar was "absorbed into the vocabulary of rock" and has continued to be influential.
Initially, the Byrds pioneered the musical genre of folk rock as a popular format in 1965, by melding the influence of the Beatles and other British Invasion bands with contemporary and traditional folk music on their first and second albums, and the hit singles "Mr. Tambourine Man" and "Turn! Turn! Turn!". As the 1960s progressed, the band was influential in originating psychedelic rock and raga rock, with their song "Eight Miles High" and the albums Fifth Dimension (1966), Younger Than Yesterday (1967), and The Notorious Byrd Brothers (1968). The band also played a pioneering role in the development of country rock, with the 1968 album Sweetheart of the Rodeo representing their fullest immersion into the genre.