Charles Walter Rainey III (born June 17, 1940 in Cleveland, Ohio, United States) is an American bass guitarist who has performed and recorded with many well-known acts, including Aretha Franklin, Steely Dan, and Quincy Jones.

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.

While his “sideman” philosophy of bass has not brought him the level of recognition of star players such as Jaco Pastorius, Rainey has recorded extensively.

On November 5, 2011, Rainey had a stroke.