Lou Silver Harrison (May 14, 1917 – February 2, 2003) was an American composer. He was a student of Henry Cowell, and Arnold Schoenberg. He worked with noted Javanese Gamelan musician K. P. H. Notoprojo.
Harrison is particularly noted for incorporating elements of the music of non-Western cultures into his work, with a number of pieces written for Javanese style gamelan instruments, including ensembles constructed and tuned by Harrison and his partner William Colvig. The majority of his works are written in just intonation rather than the more widespread equal temperament. Harrison is one of the most prominent composers to have worked with microtones.