William Mayne was a British children's fiction writer.
William Mayne may also refer to: William Mayne, 1st Baron Newhaven (1722–1794), MP for Canterbury, Carysfort and Gatton William Mayne (Australian politician) (1808–1902), New South Wales politician William Mayne (officer) (1818–1855), English army officer in the service of the East India Company William Cyril Mayne (1877–1962), English clergyman and classical scholar