(Latin: Hugo Cavellus; anglicised: Hugh MacCaghwell; 1571 – 22 September 1626), was an Irish Franciscan theologian and Archbishop of Armagh.

Mac Cathmhaoil was born in 1571[1] at Saul, County Down, and received his earliest education in his native place; he trained at one of the bardic schools still operating in Ulster.

Mac Cathmhaoil was sent by the Earl as special messenger to the Court of Spain to solicit aid for the Ulster forces.

During his stay at Salamanca, where the Court then resided, he frequented the schools of the university and took doctor's degrees in divinity.

It was principally due to his great influence at the Spanish Court that the Irish Franciscan College of St. Anthony was founded at Leuven (Louvain).

In scouring the north and midlands of Ireland for all available manuscripts, to write an ecclesiastical history of Ireland, his associates (Mícheál Ó Cléirigh, a trained historian) and Aodh Mac an Bhaird (Hugh Ward) are credited with saving many of the Irish manuscripts that still survive.

On 17 March 1626, Pope Urban VIII, passing over all the other candidates, appointed Mac Aingil to succeed Peter Lombard as Archbishop of Armagh and Primate of All Ireland.

Philosophy Portal Mac Cathmhaoil composed four Christmas carols in Irish, including A Naoidhe Naoimh (O Holy Child).