William Horatio Clarke (Newton, Massachusetts, March 8, 1840 - 1913) was an American organist. He was organist, successively in Norwood, Dedham, Boston and Woburn, moving later to Dayton (Ohio), where he was named superintendent of public schools. In the Clarigold Hall in Reading (Massachusetts) he founded a famous music chapel, which he endowed with a magnificent organ, his own work. In addition, he collaborated in music newspapers and magazines.