Cú Roi

King of Munster. Cú Roi (Cu Roi) was the father of Lugaid Mac Cu Roi (Lewy). In the Welsh Culhwch and Olwen, Cú Roi was equated with Cubert son of Daere.

During Bricriu's Feast, Cu Roi transformed himself into a giant or demon named Uath ("Horror"). Uath challenged the three Ulster champions to a beheading game to determine who was entitled to have the champion's portion in a feast. Only Cú Chulainn (Cu Chulainn) accepted his challenge and was named champion of Ireland.

However, Cu Roi's beautiful wife Bláithíne (Blathnat), possible daughter of Conchobar, was in love with Cu Chulainn, and secretly sent a letter to him to take her away from her husband. Cu Chulainn attacked the dun and killed Cu Roi in a battle. As Cu Chulainn set about to take her away, one of Cu Roi's loyal servants pulled himself and Blathnat over the dun's wall, which killed the pair.

Later, Lugaid avenged his father's death by mortally wounding Cu Chulainn.