Ó Macassa
Ó MACASSA—II—O Mackessy, Macassy, Mackessy, MacKessy, MacAssie, Maxey; 'descendant of Macus' (a form of Maghnus); the name of a family of Ui Fidhgheinte who were anciently lords of Corca Oiche in the modern barony of Glenquin, in the west of Co. Limerick, but dispossessed soon after the Anglo-Norman invasion by a branch of the Fitzgeralds and dispersed through Munster and Leinster.
Alphabetical Index to Irish Surnames