Connor O'Brien, 3rd Earl of Thomond

Connor O'Brien, 3rd Earl of Thomond (1534?–1581), called Groibleach (or Long-nailed), grandson of Conor O'Brien (d. 1539); succeeded to the earldom, 1553; his right to the lordship of Thomond was disputed by his uncle, Donnell; confirmed in his possessions by Thomas Radclyffe, 3rd Earl of Sussex in 1558, who proclaimed his uncles traitors, though peace was not established until 1565. He intrigued with Fitzgerald in 1569, and fled to France; returned to Ireland and received pardon, 1571, with the restoration of his lands, 1573.

O'Brien, was, called Groibleach, or the "long-nailed", was the eldest son of Donough O'Brien, 2nd Earl of Thomond, and Helen Butler, youngest daughter of Piers Butler, 8th Earl of Ormond. He succeeded to the earldom on the death of his father in April 1553. His right was challenged by his uncle Donnell, who was formally inaugurated O'Brien and chief of the Dal Cais. Obliged to surrender Clonroad, the usual residence of the O'Briens, Conor retired to the castle of Doonmulvihill, on the borders of Galway, where he was besieged by Donnell, but relieved by his kinsman Thomas Butler, 10th Earl of Ormond.

Subsequently, Donnell petitioned for official recognition as chief of Thomond, and St. Leger, though unable to grant his request, promised to write to Queen Mary in his favour. Matters continued in this uncertain state till the summer of 1558, when the Earl of Sussex, having marched to Limerick with a large army, caused Donnell and Teige and Donough, sons of Murrough, 1st Earl of Thomond, to be proclaimed traitors, and Conor to be reinstated in his possessions. Donnell took refuge with Maguire in Fermanagh, and Teige and Donough found a powerful protector in Gerald FitzGerald, 15th Earl of Desmond.

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