Reverend William Frederick Archdall Ellison FRAS (28 April 1864 – 31 December 1936) was an Irish clergyman, Hebrew scholar, organist, avid amateur telescope maker, and, from 1918 to 1936, director of Armagh Observatory in Armagh, Northern Ireland.
He was the father of Mervyn A.
Ellison, the senior professor of the School of Cosmic Physics at Dunsink Observatory from 1958 to 1963.