Leighton Lucas (5 January 1903 – 1 November 1982) was an English composer and conductor. Born into a musical family (his father, Clarence Lucas, was also a noted composer), he began his career as a dancer for Sergei Diaghilev's Ballets Russes (1918–21). He became a ballet conductor at 19, as well as a self-taught composer of religious works and film music.
He is particularly noted for his film compositions, including the scores for Target for Tonight (1941), Alfred Hitchcock's Stage Fright (1950), Ice-Cold in Alex (1958) and the incidental music for The Dam Busters (based on the title march by Eric Coates).
Benjamin Britten wrote that Lucas's Partita (1934) for piano and chamber orchestra was "very interesting - especially quite lovely Sarabande." Lucas's 'Sinfonia Brevis' (1936?) for horn and 11 instruments may be one of the earliest British scores to incorporate Balinese gamelan effects (it was heard by Benjamin Britten who went on to use such effects in his music from Paul Bunyan).