Keith John Moon (August 23, 1946 – 7 September 1978) was an English musician, best known for being the drummer of English rock group The Who. He gained acclaim for his exuberant and innovative drumming style, and notoriety for his eccentric and often self-destructive behaviour, earning him the nickname "Moon the Loon". Moon joined The Who in 1964. He played on all albums and singles from their debut, 1964's "Zoot Suit", to 1978's Who Are You, which was released three weeks before his death.

Moon was known for dramatic, suspenseful drumming—often eschewing basic back beats for a fluid, busy technique focused on fast, cascading rolls across the toms, ambidextrous double bass drum work and wild cymbal crashes and washes. He is mentioned in the Rock and Roll Hall of Fame as one of the greatest of all rock and roll drummers, and was posthumously inducted into the Rock Hall as a member of The Who in 1990. Moon's legacy, as a member of The Who, as a solo artist, and as an eccentric personality, continues to garner awards and praise, including a Rolling Stone readers' pick placing him in second place of the magazine's "best drummers of all time" in 2011, nearly 35 years after his death.