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O'Cleary (Irish: Ó Cléirigh) is the surname of a learned Gaelic Irish family whose members appear in historical records dating to the mid-Medieval Period. The O'Clearys were descended from the Connachta's Uí Fiachrach kindred and had been rulers of Uí Fiachrach Aidhne, a kingdom in what is now the south of County Galway. The name of the family means descendent or son of the Scribe. It is the oldest recorded surname in Europe having been first recorded in 916

Ó Cléirigh
Cleary arms
Parent houseUí Fiachrach Aidhne
CountryKingdom of Connacht
FounderCleireach mac Ceadach
Final rulerMhic Mac Comhaltan Ua Cleirigh
Cadet branchesCoulton

The family were subsequently expelled from their land by their cousins, the Clan Ó Seachnasaigh (O'Shaughnessy). From the early 11th or 12th century, they were based in Tír Chonaill, located in modern-day County Donegal, where they served as poet-historians, scribes and secretaries to the O'Donnell dynasty of Tyrconnell. They authored the Ó Cléirigh Book of Genealogies. The clan Cleary and its branches also appeared in Scotland (sometimes known as McCleary), due to the historical connection and exchange between the two countries, much like the Campbells.


Naming conventionsEdit

The name has been Anglicised variously as O'Clery, Cleary, Clark, Clarke and Clarkson.

Male Daughter Wife (Long) Wife (Short)
Ó Clérigh[1] Ní Chlérigh Bean Uí Chlérigh Uí Chlérigh


Notable members of the clan included:

Ó CléirighEdit




Other institutionsEdit

See alsoEdit


  1. ^ "Ó Clérigh". Sloinne. 5 December 2015.


External linksEdit