John Clifford Farrar (; born 8 November 1946) is an Australian-born music producer, songwriter, arranger, singer and guitarist. As a musician, Farrar is a former member of several rock and roll groups including The Mustangs (1963–64), The Strangers (1964–70), Marvin, Welch & Farrar (1970–73), and The Shadows (1973–76); in 1980 he released a solo eponymous album. As a songwriter and producer he worked with Olivia Newton-John from 1971 to 1989. He wrote her number-one hit singles: "Have You Never Been Mellow" (1975), "You're the One That I Want" (1978 duet with John Travolta), "Hopelessly Devoted to You" (1978), and "Magic" (1980). He also produced the majority of her recorded material during that time including her number-one albums, If You Love Me, Let Me Know (1974), Have You Never Been Mellow (1975) and Olivia's Greatest Hits Vol. 2 (1982); and he was a co-producer of Grease (1978) – the soundtrack for the film of the same name. Farrar also produced Newton-John's first United States number-one hit single, "I Honestly Love You", which was awarded the Grammy Award for Record of the Year in 1975. In 1969 Farrar married fellow Australian singer, Pat Carroll – formerly Newton-John's singing partner. In July 1970 Farrar and Carroll relocated to the United Kingdom and from late 1975 they have resided in the US. They are the parents of Sam Farrar (Phantom Planet bass guitarist) and Max Farrar (Golden Ghost guitarist and keyboardist).