(?1590–1643), annalist, and chief compiler of the Annals of the Four Masters. Born in Kilbarron, near Ballyshannon, Co. Donegal, into the Ó Cléirigh learned family, his baptismal name was Tadhg, but when he was professed in Louvain as a Franciscan lay brother, he took the name of Míchéal. He was trained as a scholar in the family tradition, and when Aodh Mac an Bhaird in Louvain was co-ordinating the research there and in Ireland which led to John Colgan's Actà Sanctorum Hiberniae (1645) and other publications, he sent Ó Cléirigh home in 1626 to gather manuscript material and to check dates and sources with living Irish scholars. He was based in the Franciscan friary at Bundrowes, Co. Donegal, but for eleven years he travelled the country, visiting friaries, convents, and lay learned schools, transcribing and checking, and sending fresh copies back to Louvain. For the Réim Ríoghraídhe (Succession of the Kings) (completed November 1630), he had the assistance of three lay scholars: Fear Feasa Ó Maoilchonaire from Co. Roscommon, Cuchoigríche Ó Cléirigh, his cousin from Co. Donegal, and Cuchoigríche Ó Duibhgeannáin from Co. Leitrim. These three, along with Ó Cléirigh, were called the ‘Four Masters’ by Colgan in his preface to Acta Sanctorum Hiberniae, in recognition of the fact that they undertook the great bulk of the work leading to the Annals of the Four Masters. In undertaking the Annals Ó Cléirigh was greatly extending his original brief. They began work at Bundrowse in January 1632 and finished on 10 August 1636. In 1637 Ó Cléirigh returned to Louvain, where he prepared his Irish lexicon, Foclóir nó Sanasán Nua (A New Vocabulary or Glossary) (Louvain, 1643).
From The Concise Oxford Companion to Irish Literature in Oxford Reference.