Frans Bak (born 7 February 1958) is a Danish composer, choral conductor, saxophonist, and pianist. He is a graduate of the Royal Danish Academy of Music, and is known for his work as a jazz performer and composer of film music. In 1994, he founded a composer's association Den 3. Vej.

He is best known for his work as a film composer creating the score for the Danish television series Forbrydelsen as well as the American remake, The Killing, on AMC. His latest projects include Lilyhammer on NRK1/Netflix, starring Steven Van Zandt and the British adaption of the Ruth Rendell novel Thirteen Steps Down.