Rudolf Maximilian Butler, RIAI, FRIBA, RSAI, RHA, RIA, (30 September 1872 – 3 February 1943) was a well-known Irish Roman Catholic ecclesiastical architectural historian, academic, journalist, and architect of Dublin active, throughout late-nineteenth-century to mid-twentieth-century Ireland. He resided and worked at 23 Kildare Street, Dublin until he designed a new residence for himself at 73, Ailesbury Road. He was brought up a Moravian and may have remained in that faith throughout his life, however, he designed all of his churches for the Roman Catholic Church, particularly for the Passionist Fathers. He was a founding member of the AAI in 1896, editor of the Irish Builder from 1899 to 1935, and professor of architecture at University College, Dublin.