William S. Fischer (born March 5, 1935, Shelby, Mississippi) is an American keyboardist, saxophonist, arranger, and composer. Fischer worked early in his career with blues and R&B musicians, playing in the 1950s with Ray Charles, Guitar Slim, Big Joe Turner, and Muddy Waters. He took a bachelor's degree at Xavier University in 1956 and a master's in Colorado College in 1962, after which he returned to Xavier as a teacher. He also studied at the Vienna Academy of Music and Performance in 1965–66. From 1967 to 1975, he taught in New York public schools.