The Clan Murtagh O'Conor (Irish: Clan Muircheartaigh Uí Conchobhair) were descendants of Irish High-King Toirdelbach Ua Conchobair, through his son, Murtogh Moynagh O'Conor (d.1210), tánaiste of Connacht. They have been defined by Katherine Simms as:
"... the earliest, most aristocratic and best documented example of increasing nomadism in the northern half of Ireland in the late middle ages. ... In spite of the fact that they were a very numerous branch of the O'Conor family, who supplied five kings to the throne of Connacht, they seem to have vanished away in the early fifteenth century, never to be heard of again."[1]