William Fish may refer to:
- William Fish (Scarborough MP) (fl. 1580s), MP for Scarborough
- William Fish (musician) (1775–1866), English violinist, organist and composer
- William H. Fish (1849–1926), Associate Justice and Chief Justice of the Supreme Court of Georgia
- William Fish (South African politician) (fl. 1920s), Mayor of Cape Town
- W. B. Fisher (born William Bayne Fish, 1916–1984), British geographer
- Will Fish (born 2003), English footballer
- Billy Fish, fictional character in the 1975 film, The Man Who Would Be King