John Lee Clayton Jr. (born August 20, 1952) is an American jazz musician, classical double bassist, arranger, and composer.

He is the brother of saxophonist Jeff Clayton, with whom he formed The Clayton Brothers; and The Clayton–Hamilton Jazz Orchestra with Jeff Hamilton. Clayton began studying double bass at age 16 with Ray Brown. Three years later, he was bassist on the Henry Mancini’stelevision series The Mancini Generation. In 1975, he graduated from Indiana University.

He went on to tour with the Monty Alexander Trio and the Count Basie Orchestra, before taking the position of principal bass in the Amsterdam Philharmonic Orchestra in Amsterdam, Netherlands. After five years he returned to the U.S. for a break from the classical genre and, in 1985, co-founded the Clayton-Hamilton Jazz Orchestra with his brother, saxophonist Jeff Clayton, and drummer Jeff Hamilton. He also performed in a duo as the Clayton Brothers with musicians such as Bill Cunliffe and Terell Stafford.