Muircheartach Mac Lochlainn (old spelling: Muirchertach Mac Lochlainn) was king of the Cenél nEógain, Tyrone and High King of Ireland from around 1156 until his death in 1166.
The Uí Catháin of Cenél nEógain originated in the Laggan area of County Donegal, and from there moved eastwards in the twelfth century, ousting the Uí Conchobair from Keenaght and retaining their lordship of Keenaght and Coleraine until the seventeenth century.