William Ayerst (1830–1904) was an English clergyman and missionary. He was born at Dantzig on 16 March 1830, the eldest son of William Ayerst, vicar of Egerton, Kent. He studied at King's College, London from 1847–9, and graduated from Gonville and Caius College, Cambridge with a B.A. in 1853, and an M.A. in 1856. After being ordained as a deacon in 1853 and priest in 1854, he was appointed to All Saints, Gordon Square (1853–5), St Paul's, Lisson Grove (1855–7), and St Giles in the Fields (1857–9).