MacCarthy MacCarthy MacCarthy (Irish: Mac Cárthaigh), also spelled Macarthy, McCarthy or McCarty, is a Gaelic Irish clan originating from Munster, an area they ruled during the Middle Ages. It was and continues to be divided into several great branches. The MacCarthy Reagh, MacCarthy of Muskerry, and MacCarthy of Duhallow dynasties were the three most important of these, after the central or MacCarthy Mór line. Their name, meaning "son of Cárthach" (whose name meant "loving"), is a common surname that originated in Ireland. As a surname, its prevalent spelling in the English language is McCarthy. Several variants are found, such as McCarty
Eolais mac Biobhsach manuscripts going back almost two hundred years. O'Donovan claimed the family name ( "descendent of Eolais") is still found anglicised as "Olus" or "Olis". two instances of the surname corrupted as "Oelase" and "Olase", are found in the Irish Fiants for Leinster. The surname must be very rare. Eolais mac Biobhsach Eolais "mac Biobhsach" (alias " "knowledge", anglicized "Wallis", "Olis" or "Olus" ) was a chieftain of 10th century Gaelic Ireland. He is noted as the first "full chieftain of Conmaicne Réin". His descendants, "the Muintir Eolais", expanded into the territory of present day south county Leitrim, and parts of