Leonard Niehaus (June 1, 1929 – May 28, 2020) was an American alto saxophonist, composer and arranger on the West Coast jazz scene. He played with the Stan Kenton Orchestra and served as one of Kenton's primary staff arrangers. He also played with Ray Vasquez and trombonist and Vocalist, Phil Carreon and other jazz bands on the U.S. West Coast. Niehaus had a close association as composer and arranging to motion pictures produced by Clint Eastwood.