William Parker (b. Bronx, New York City, New York, January 10, 1952) is an American free jazz double bassist.
A strong supporting player and striking soloist, Parker is one of few jazz bassists who regularly plays arco.
While Parker has been active since the early 1970s, he has had a higher public profile since the early 1990s. He is a vital musician in the New York City experimental jazz scene.
Parker first came to public attention with pianist Cecil Taylor. He has long been a member of saxophonist David S. Ware's quartet, and is a member of the cooperative Other Dimensions In Music.
Parker has recorded and performed with many musicians, including Matthew Shipp, Hamid Drake, Daniel Carter, Peter Brötzmann, Bill Dixon, Charles Gayle, Roscoe Mitchell, Butch Morris, DJ Spooky and Mat Maneri.
The album Sound Unity was chosen as one of Amazon.com's Top 100 Editor's Picks of 2005.