O Connor: O Conchobhair. The name of six distinct and important septs. In Connacht there were O'Connor or O'Conor Don (of which was the last high king of Ireland) with its branches O'Connor Roe and O'Conor Sligo; also O' Connor Flay (ie of Offaly), O'Connor Kerry O'Connor of Corcomroe (north Clare). The prefix O, formerly widely discarded, has been generally resumed.