The Irish surname O'Casey is an anglicized form of the Gaelic name Ó Cathasaigh meaning “descendant of Cathasach,” a byname meaning “vigilant, or noisy.” Six distinct septs of this name existed in Ireland: the most important of these in early times were erenaghs of Devenish, County Fermanagh, where the family held church property from generation to generation. A minor sept having the prefix "Mac", instead of "O", was located in County Monaghan, and three bishops named Mac Casey occupied the see of Clogher in the 14th Century. Another leading O'Casey family were Lords of the Suaithni (comprising the modern barony of Balrothery West, County Dublin), and a further family were erenaghs of Clondara in the barony of Athlone, County Roscommon. The Dalcassian septs were seated at Liscannon, County Limerick, and near Mitchelstown, County Cork; the name is now most numerous in these Munster counties. John Keegan Casey (1846 - 1870) was a Gaelic poet.
O'CASEY FAMILY CREST PENDANT