Owen O'Moriarty (Irish:Eoin Ó Muircheartaigh) was a Gaelic Irish warrior notable for his part in the final stages of the Desmond Rebellion and the death of Gerald FitzGerald, 15th Earl of Desmond in 1583.
The Moriarty were a clan who inhabited the southern side of Tralee Bay in County Kerry led by Maurice O'Moriarty. Following a series of defeats and a sustained campaign against his forces, the Earl of Desmond had gone into hiding in western Kerry. In November 1583 a raiding party of Desmond's men attacked a group of O'Moriartys, stealing their cattle and robbing women and children.
The O'Moriarty's sought permission from a local Royal commander Sir William Stanley to take revenge. Accompanied by several government soldiers, a party of warriors led by Owen pursued Desmond into the Slieve Mish Mountains. They discovered the Earl sheltering without any guards in a cabin. O'Moriarty attempted to take Desmond prisoner, seizing him and arresting him in the name of the Queen and the Lord General Ormond. However fearing that some of Desmond's men were approaching, they cut off the Earl's head and abandoned the remainder of his body. The reward paid out for Desmond's head by the government was a thousand pounds.