O'Connor of Connacht

Gaelic Irish royal dynasty of Connacht. Having established dominance over the O'Rourkes and other major dynasties of Connacht in the early 11th century, the O'Connors asserted tenuous claims to the high kingship of Ireland over the next century which were never fully accepted. In 1166 the high king Rory O'Connor (died 1198) deposed Dermot MacMurrough, King of Leinster, who retaliated by inviting a number of Anglo-Norman barons to support his reinstatement; their arrival in 1169 was followed by a full-scale Anglo-Norman invasion under Henry II in 1171. Although Rory O'Connor made peace with Henry II at Windsor in 1175, by which he retained all of Connacht, internecine disputes paved the way for Anglo-Norman penetration into Connacht led by the de Burghs. By the time of the death without heir of Áodh, the last king of Connacht, in 1274, the O'Connors had already been reduced to vassals of the de Burghs.

The O'Connors then split into two dynasties: O'Connor Roe (the red-haired) and O'Connor Don (the brown-haired). The former became vassals of the de Burghs while the latter retained a position of some independence in Connacht down to modern times.

O'Connor Faly (Offaly) was an unrelated dynasty that survived between the often hostile Anglo-Irish lords of Ormond and Kildare until 1556, when the Tudor government undertook a major plantation in their territory along with that of their neighbours, the O'Moores in County Laois.