Patrick MacMahon, O.F.M. (died c.1572 or c.1575) was Bishop of Ardagh in Ireland, recognised at various times by both the Roman Catholic church in Ireland and the Church of Ireland. His appointment to the see was approved by the Vatican on 14 November 1541. The Reformation in Ireland had begun, but there was not yet a definitive break between, on the one hand, the hierarchy recognised by the Roman Curia and, on the other hand, the established church recognised by the Dublin Castle administration of the English king Henry VIII. The Diocese of Ardagh was in the Annaly region of the Farrell clan, of whom Richard O'Ferrall had secured the temporalities of the diocese in July 1541. George Cromer, the Church of Ireland Archbishop of Armagh and primate of all Ireland, recognised O'Ferrall and had