William Melvin Mitchell (November 3, 1926 – April 18, 2001) was an American jazz tenor saxophonist.

Mitchell was born in Kansas City, Missouri. He and his family moved to Detroit, where he received early music education at Cass Tech. He was known for his close association with trumpeter Thad Jones, who was also from Detroit, and worked in several big bands, including Woody Herman‘s when he replaced Gene Ammons. In 1949 Mitchell recorded with the Milt Buckner band, as well as making several recordings with Thad Jones.

From 1951 to 1954, Mitchell led the house band at the Blue Bird Inn in Detroit. The band operated in different configurations, including with drummer Oliver Jackson and his bassist brother Ali; as a quartet with Terry Pollard, Beans Richardson, and Elvin Jones; as a quintet including Thad Jones; and, for several months in 1953, with Miles Davis as a guest soloist.

From 1956 to 1957 he played with Dizzy Gillespie in his big band. From 1957 until 1961 and from 1966 to 1967 Mitchell played with Count Basie. In the early 1960s he co-led a group with Al Grey, The Al Grey Billy Mitchell Sextet, which won the Down Beat magazine new band award in 1962. Mitchell performed and recorded with the Kenny Clarke/Francy Boland Big Band in Europe in the late 1960s and early 1970s. He was musical director for Stevie Wonder for a short time during this period. He died in Rockville Centre, New York, in 2001.

He is not to be confused with Billy Mitchell the jazz pianist and keyboardist whose career was with Optimism Records in the 1980s.