William Henry Mayne M.D., L.R.C.S., (ca. 1816 – 25 December 1857) was a British orthodox physician who converted to homeopathy. Mayne was a member of the British Homeopathic Society from its inception in 1844. Mayne was a member of the Medical Council of the London Homeopathic Hospital, a Medical Officer at the Westminster and Lambeth Homeopathic institute and Dispensary with Edward Hamilton, and at the West End Homeopathic Dispensary with Jones and Guthrie, and Assistant Demonstrator at the Blenheim Street School of Medicine founded by surgeon and naturalist Joshua Brookes.
William Henry Mayne wrote On the use of Caster oil as a powerful Anti Spasmodic, with satisfactory results from its use in cholera, diarrhoea and dry bellyache, On the use of the accustomed stimulus in delerium tremens.
J. Mayne M. D. was a Steward at the Annual Festival in aid of the funds of the Charity, and in commemoration of the opening of the London Homeopathic Hospital on Thursday, the 10th of April 1851.