Stu Williamson (May 14, 1933 – October 1, 1991) was an American jazz trumpeter and valve trombonist.

Born in Brattleboro, Vermont, Williamson was the younger brother of jazz pianist Claude Williamson. Williamson relocated to Los Angeles in 1949 and became a regular on the West Coast scene, playing with Stan Kenton (1951, 1954-1955), Woody Herman (1952-1953), Billy May, and Charlie Barnet. Between 1954 and 1958 he played intermittently with Shelly Manne, and was a ubiquitous session musician until 1968, when he retired from music.