Galt MacDermot (born 18 December 1928 in Montreal, Quebec) is a Canadian pianist, composer and writer of musical theatre. He was educated at Upper Canada College and Bishop's University (Sherbrooke, Quebec). He was trained in music in South Africa and made a study of African music his specialty.

He is best known as the composer of the groundbreaking 1960s rock musical Hair, which ran for nearly 2000 performances in both London and New York, won a Grammy Award in 1969, and was made into a film in 1979. MacDermot is also popular amongst collectors of jazz, funk and film soundtracks, for the scores he created to minor productions such as Woman is Sweeter and Rhinoceros.