O'Rourke, Thaddeus (‘Thady’) Francis (1659?–1735), catholic bishop of Killala, was probably born in Breffni, north Leitrim, the son of Tiernan O'Rourke and Isabel McDonagh. About 1674 he joined the Irish Franciscans on the continent, given that the friars declared him a jubilarian in 1724. He obtained an STL and lectured for a while, probably at the Irish Franciscan College of the Immaculate Conception in Prague. Later he served as guardian of the friary at Jamestown (1689–93) and that at Dromahair (1697–9, 1700–02). Given the difficulties of those years, these were probably nominal appointments. His father or brother Tiernan O'Rourke fled Ireland after the Treaty of Limerick (1691) and served gallantly in the Austrian army; he was killed at the battle of Luzzara in the Po valley in August 1702. Prince Eugene of Savoy, commander of the Austrian forces, appointed O'Rourke his chaplain and private secretary, giving him a gold cross and diamond ring.
The nomination of Irish bishops was then at the discretion of the Stuart monarchs in exile in France. James III, the Old Pretender, nominated O'Rourke to the diocese of Killala in 1703. The brief was allowed to lapse, probably because it was addressed to another friar of the same name. Prince Eugene introduced O'Rourke to the Emperor Leopold I. Before Leopold died in 1705 he gave the friar letters of commendation to Queen Anne and a personally signed passport. A new brief appointing O'Rourke to Killala was issued on 15 March 1707. The bishop-elect travelled to London and received an audience with Queen Anne. Now under royal protection from the effects of the Banishment Act of 1697, he made his way to Dublin. There he arranged his consecration in Newgate jail by Patrick Donnelly (qv), bishop of Dromore, assisted by Edmund Byrne, archbishop-elect of Dublin, and Fergus O'Farrell, archdeacon of Ardagh.
O'Rourke was the first bishop of Killala since 1661. Unable to reside in the diocese, he took up residence with his brother-in-law, Counsellor Terence MacDonagh (qv), at Creevagh, Co. Sligo. The new bishop had a difficult task, with some nineteen priests trying to look after twenty-two parishes. When visiting his diocese, he stayed in the cottages of the ordinary people. One of the few active catholic bishops in Ireland at the time, he confirmed many people, ordained priests in several parts of the country, and consecrated a number of bishops. Queen Anne changed her religious policies after the death of Emperor Joseph I in 1711. No longer immune from prosecution, O’Rourke fled to the isolated area around Meelick friary in east Galway and hid his identity under the name of Mr Fielding. After the death of Terence MacDonagh in 1713, he took up residence with the O'Conors of Bellanagare, Co. Roscommon, where he acted as tutor to his nephew, the antiquarian and writer Charles O'Conor (qv) (1710–91). He had to go into hiding again in 1732–4. O'Rourke died, probably at Bellanagare, on 13 March 1735 and was buried at Creevelea friary near Dromahair.