David Justin Hayward is an English musician. He was the guitarist and frontman of the rock band the Moody Blues from 1966 until that group's dissolution in 2018. He became the group's principal vocalist and its most prolific songwriter over the 1967–1974 period, and composed several international hit singles for the band.

The Moody Blues were an English rock band formed in Birmingham in May 1964. The band initially consisted of drummer Graeme Edge, guitarist/vocalist Denny Laine, keyboardist/vocalist Mike Pinder, multi-instrumentalist/vocalist Ray Thomas, and bassist/vocalist Clint Warwick. Originally part of the British beat and R&B scene of the early–mid 1960s, the band came to prominence with the UK No. 1 and US Top 10 single "Go Now" in late 1964/early 1965. Laine and Warwick left the band by the end of 1966, being replaced by guitarist/vocalist Justin Hayward and bassist/vocalist John Lodge. They embraced the psychedelic rock movement of the late 1960s, with their second album, 1967's Days of Future Passed, being a fusion of rock with classical music that established the band as pioneers in the development of art rock and progressive rock. It has been described as a "landmark" and "one of the first successful concept albums".