Murtogh Moynagh O'Conor (Irish: Muirchertach Muimhnech Ua Conchobair), prince of Connacht, Ireland, flourished 1156–1210.
He was one of three sons of Tairdelbach arrested in 1156 by their brother, Ruaidrí Ua Conchobair, on the death of their father.
Before his death Muirchertach became Tánaiste himself and held control of much of present-day County Mayo.
His sons were subsequently expelled from this area in the conquest of Connacht by Richard Mór de Burgh, 1st Baron of Connaught in 1235.
She is described in the Annála Connacht as: The Mac Diarmata family also had a recently acquired lordships in central Mayo, north of the Clan Muircheartaigh.