Cú Roí was a King of Munster (the southern province of Ireland) in Irish Mythology.
Cú, a native Irish word, translates to hound and similarly Roí to plain or field. Together Cú Roí refers to ‘Hound of the Battlefield’.
Cú Roí was known for super-human strength and mastery of disguise. Cú Roí was a contemporary of Cú Chulainn, the legendary warrior from Ulster (Irelands’ northern province) in the traditional Irish mythos. Cú Roí and Cú Chulainn have a fraught relationship, sometimes allies, sometimes enemy’s in great quests across Ireland and the Irish Sea.
Cú Roí is mentioned in Welsh literature recounting tales of King Arthur and his Irish allies. Genealogically, Cú Roí belongs to the Clanna Dedad, a leading dynasty of the Érainn, and was cousin to the famous monarch Conaire Mór, a High King of Ireland.
More information on Cú Roí and related characters may be found here