O’Hegarty, ó hEigceartaigh A Gaelic surname meaning descendant from éigceartach meaning ‘unjust’. A sept of the Cineál Eoghain. A sept of the Eóganacht in Carbery in Cork. In 1890 Hegarty was principally found in Cork, Donegal, Clare, Derry and Mayo and the estimated number of bearers was 4,480 (including variants). In the United States Hegarty is the 9,960th most numerous surname with an estimated 2,750 bearers.