John Douglas Lord (9 June 1941 – 16 July 2012) was an English keyboardist and composer. In 1968, Lord co-founded the hard rock band Deep Purple, and he became regarded as its leader in the early years. Lord performed on most of the band's most popular songs; he and drummer Ian Paice were the only continuous presence in the band between 1968 and 1976, and also from when it was re-established in 1984, until Lord's retirement in 2002. He also spent time in the bands Whitesnake, Paice Ashton Lord, the Artwoods, the Flower Pot Men and Santa Barbara Machine Head.

Lord became known for his pioneering work in fusing rock with classical or baroque forms, especially with Deep Purple. His distinctive organ playing during Deep Purple's hard rock period was essential to the band's signature heavy sound and contributed to the early development of heavy metal. On 11 November 2010, he was inducted as an Honorary Fellow of Stevenson College in Edinburgh, Scotland. On 15 July 2011, he was awarded an honorary Doctor of Music degree at De Montfort Hall by the University of Leicester. Lord was posthumously inducted into the Rock and Roll Hall of Fame on 8 April 2016 as a member of Deep Purple.