Louis Grabu, Grabut or Grebus was a French composer and violinist.

Charles II of England appointed him as a composer in 1665, and with the death of Nicholas Lanier in 1666 he became the second person to hold the title Master of the King's Musick. He adapted Robert Cambert's opera Ariadne for a London performance in 1674, and wrote music for John Dryden's Albion and Albanius in 1685.