Keith Noel Emerson (born 2 November 1944) is an English keyboardist and composer. He was formerly a member of the Keith Emerson Trio, John Brown's Bodies, The T-Bones, The V.I.P.'s, P.P. Arnold's backing band, The Nice, and Emerson, Lake & Palmer (ELP), one of the early supergroups. Emerson first found success with The Nice in the late 1960s before going on to become a founding member of ELP in 1970. ELP were critically and commercially successful through much of the 1970s, becoming one of the best-known progressive rock groups of the era. Following the break-up of ELP, circa 1979, Emerson had modest success with Emerson, Lake & Powell in the 1980s as well as with 3, with the album To the Power of Three. ELP reunited during the early 1990s, releasing the album Black Moon. Emerson also reunited The Nice in 2002 for a tour. His latest album, Keith Emerson Band featuring Marc Bonilla, was released in 2008.

Along with contemporaries Richard Wright of Pink Floyd, Tony Banks of Genesis, Billy Ritchie of Clouds, Rick Wakeman of Yes, and Jon Lord of Deep Purple, Emerson is widely regarded as one of the top keyboard players of the progressive rock era. Allmusic refers to Emerson as "perhaps the greatest, most technically accomplished keyboardist in rock history".