Mitch Leigh (born Irwin Stanley Michnick; January 30, 1928 – March 16, 2014) was an American musical theatre composer and theatrical producer best known for the musical "Man of La Mancha." Born in Brooklyn, New York, he grew up in the Brownsville neighborhood and was the son of a Ukrainian immigrant. After serving in the U.S. Army, Leigh graduated from Yale University with a Bachelor of Music in 1951 and a Master of Music in 1952, studying under Paul Hindemith.

Leigh began his career as a jazz musician and composed music for radio and television commercials. He gained prominence with "Man of La Mancha," which opened on Broadway in 1965 and ran for 2,328 performances in its original engagement. Despite subsequent Broadway ventures like "Chu Chem" and "Cry for Us All" not achieving similar success, Leigh remained a significant figure in musical theatre. He also contributed to television, creating memorable jingles such as "Nobody Doesn't Like Sara Lee."

In academia, Leigh helped establish the Keith Wilson scholarship at the Yale School of Music and had a building named in his honor at the institution. He was married twice, first to Renee Goldman and later to Abby Kimmelman, and had three children, including a daughter named Eve. Leigh's contributions to musical theatre were recognized with awards such as the Tony Award and the Contemporary Classics Award.