William Horsley (18 November 1774 – 12 June 1858) was an English musician. His compositions were numerous, and include amongst other instrumental pieces three symphonies for full orchestra. More important are his glees, of which he published five books (1801–1807) besides contributing many detached glees and part songs to various collections. His glees include "By Celia's Arbour," "O, Nightingale," and "Now the storm begins to lower", and his hymn tunes Horsley usually set to There is a green hill far away.