Ross Roe MacMahon (born 1698 in Enagh, Co. Monaghan) was ordained to the priesthood in 1727. He was appointed as Roman Catholic Bishop of Clogher on 8 November 1738 following the appointment of his predecessor, Bernard MacMahon, to the see of Armagh on 8 November 1737. Bishop MacMahon was himself appointed to the same see on 3 August 1747; he died in Armagh on 29 October 1748. Bishop MacMahon served as Bishop of Clogher for just under nine years.