Art mac Cuinn, aka Art Óenfer (the "lone" or "solitary" - he was the only one of his father's many children to survive to adulthood), was a legendary High King of Ireland of the 2nd century. He was the son of Conn of the Hundred Battles and father, with Achtan, of Cormac mac Airt. He died at the Battle of Maigh Mucruimhe against Lugaid mac Con, who had returned from exile with an army of foreigners. In some versions his wife is Medb Lethderg.