William Everett Preston (September 9, 1946 – June 6, 2006) was an American soul musician from Houston, Texas, raised mostly in Los Angeles, California. In addition to his successful, Grammy-winning career as a solo artist, Preston collaborated with some of the greatest names in the music industry, including the Beatles, the Rolling Stones, Little Richard, Ray Charles, George Harrison, Elton John, Eric Clapton, Bob Dylan, Sam Cooke, King Curtis, Sammy Davis Jr., Sly Stone, Aretha Franklin, the Jackson 5, Quincy Jones, Richie Sambora, and Red Hot Chili Peppers. He played the Fender Rhodes electric piano and the Hammond organ on the Get Back sessions in 1969.

Although Preston is one of several people sometimes credited as a "Fifth Beatle", he is one of two non-Beatles (the other being Tony Sheridan) to receive label performance credit on any Beatles record.