O’Leary, ó Laoghaire, ó Laoire A Gaelic surname meaning descendant of Laoghaire, which personal name meant ‘calf-herd’. A sept of the Corcu Loíghdhe, who were originally chiefs of the area around Rosscarberry in west Cork. At the time of the Cambro-Norman invasion they moved to the parish of Inchigeelagh, where they became lords under Mac Carthaigh (MacCarthy) of the area between there and Macroom. The chief of the sept resided at Carrignacurra, a mile east of Inchigeelagh. In 1890, (O’)Leary was the sixty-second most numerous surname and the estimated number of bearers was 11,000. In that year the surname was chiefly found in Cork (93 births), Kerry (38 births) and Wexford (21 births). In the United States O’Leary is the 1,836th most numerous surname with an estimated 19,250 bearers, and Leary is the 1,914th most numerous surname with an estimated 19,250 bearers. It is numerous in the state of Massachusetts.