David Justin Hayward OBE (born 14 October 1946) is an English musician. He was the guitarist and frontman of the rock band the Moody Blues from 1966 until its 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. With John Lodge's death in 2025, Hayward is the last surviving member of the classic Moody Blues lineup.

Singles written by Hayward for the Moody Blues include "Nights in White Satin", "Tuesday Afternoon", "Never Comes the Day", "Question", "The Voice", "I Know You're Out There Somewhere" and "English Sunset"; he wrote 20 of the group's 27 post-1967 singles. He also has a solo career. His first album outside the Moody Blues, Blue Jays, a collaboration with John Lodge, reached the UK top five in 1975. The single "Blue Guitar", recorded with 10cc as the backing band, reached the UK top ten in 1975, and his 1978 recording of "Forever Autumn" from Jeff Wayne's Musical Version of The War of the Worlds reached the UK top five.

In 2018 Hayward was inducted into the Rock and Roll Hall of Fame as a member of the Moody Blues and in 2022 was appointed Officer of the Order of the British Empire (OBE) for services to the music industry.

Hayward was born in Dean Street, Swindon, Wiltshire, the son of two teachers. He was educated at Shrivenham Primary School in nearby Shrivenham, Oxfordshire, and at the Commonweal School in Swindon. Tall for his age, at Commonweal School he acquired the nickname "legs". He was playing in several bands as early as the age of 15, when he bought a Gibson 335, a guitar that appears on nearly all of his records throughout his career, and a Vox AC30 amplifier. All previous guitars were "unsatisfactory" and required modification. He performed with local Swindon groups in clubs and dance halls playing mostly Buddy Holly songs. One of Hayward's early groups was All Things Bright, which opened for The Hollies and Brian Poole and the Tremeloes. When he was 18 he signed an eight-year publishing contract as a songwriter with the skiffle artist and record producer Lonnie Donegan, a move Hayward later regretted, as it meant the rights to all his songs written before 1974 would always be owned by Donegan's Tyler Music. In 1965 he answered an advertisement in Melody Maker and auditioned as guitarist for Marty Wilde and he went on to work with Wilde and his wife in The Wilde Three.

In 1966, after answering another ad in Melody Maker, this time placed by Eric Burdon of The Animals, Hayward was contacted by Mike Pinder of the Moody Blues after Burdon had passed on Hayward's letter and demo discs to Pinder. Within a few days, Hayward had replaced departing Moody Blues vocalist and guitarist Denny Laine. At the same time bassist John Lodge replaced the departed Clint Warwick.

After beginning by singing the old blues-inspired repertoire of the Moody Blues' 1964–1965 era, Hayward's initial artistic contribution to the Moody Blues was his song "Fly Me High", which was a Decca single early in 1967. It failed to chart, but gave the revised band a new direction forward from the R&B sound they had been largely producing up to that point.

Hayward's driving rocker "Leave This Man Alone" was then used as the B-side of their next single on Decca, backing Pinder's "Love And Beauty" (1967), the first Moody Blues record to feature the Mellotron. Hayward and Lodge's integration into the Moody Blues along with Pinder's use of the Mellotron sparked greater commercial success and recognition for the band, transforming them into one of pop music's biggest-selling acts.

The 1967 album Days of Future Passed, one of the first and most influential symphonic rock albums, gave rise to the Hayward-penned singles "Tuesday Afternoon" and "Nights in White Satin". The latter record went on to sell over two million copies, charting three times in the UK (1967, 1972 and 1979), and has been recorded by many other recording artists. Hayward's B-side song "Cities" was an early ecology-themed item.