Sandy Denny, born Alexandra Elene Maclean Denny (6 January 1947 – 21 April 1978), was an English singer and songwriter who has been described by Allmusic's Richie Unterberger as "the pre-eminent British folk rock singer". She emerged in the mid 1960s while still a teenager, performing on the folk revival scene where she displayed her mastery of traditional singing and interpretation. Her song, "Who Knows Where the Time Goes?", written during these early years, has been covered by numerous artists and is regarded as a classic of its type.
Over a ten year career Sandy Denny left an extensive legacy and remains influential. She is remembered for her pivotal involvement with the British folk rock movement, where as a member of Fairport Convention, she moved the band away from west coast American cover versions and into performing traditional material and original compositions. She is also noted for her duet with Robert Plant on Led Zeppelin's fourth album in 1971, on the song "The Battle of Evermore", and to date Sandy Denny remains the only guest vocalist on a Led Zeppelin album.