Moylurg was the name of a kingdom located in the north-east of Connaught, the western province of Ireland, from c.956-1585. The Kings of Moylurg were a branch of the Sil Muiredaig , who were themselves of the Ui Briuin who descended from The Connachta.

Moylurg is, in Irish, Magh Luirg an Dagda, the plain of the tracks of the Dagda. The Dagda was an ancient Irish diety, and the tracks referred to were said to be left by his large penis being dragged behind him!

The kingdom's first king, Maelruanaidh Mor mac Tadg, was a son of Tadg mac Cathal (King of Connacht 925-956) and brother to Conchobar mac Tadg, who succeded as king in 967. Maelruanaidh is said to have made a deal of some nature where, in return for abandoing any claim to the provincial kingship, he would be given Moylurg. His dynasty were known as the Clan Mulrooney, and later still took the surname of MacDermot.