Charles Walter Rainey III (born June 17, 1940) is an American bass guitarist who has performed and recorded with many well-known acts, including Aretha Franklin, Steely Dan, and Quincy Jones. Rainey is credited for playing bass on more than 1,000 albums, and is one of the most recorded bass players in the history of recorded music.

Rainey was born in Cleveland, Ohio on June 17, 1940, and grew up in Youngstown. His parents were both amateur pianists. He learned piano, violin, and trumpet as a child and majored in brass instruments in college. He attended Lane College in Jackson, Tennessee. Rainey began playing bass guitar in the military.

After leaving the military, Rainey joined a local band. His first big professional gig was playing with Big Jay McNeely. He then joined up with Sil Austin to tour Canada and New York. In 1962, Rainey joined King Curtis and his All-Star band; in 1965, they opened for The Beatles’ 1965 US tour. He joined Quincy Jones‘s big band in 1972. By the 1970s he had played with Jerome Richardson, Grady Tate, Mose Allison, Gato Barbieri, and Gene Ammons, as well as with Eddie Vinson at the 1971 Montreux Festival.