There is a story handed down, from Father to Son, about a young man named Sétanta. One day Sétanta was invited to a feast in honour of the high king Conor Mac Neasa, which was being held at the home of a local smith named Culann. Sétanta arrived late and, upon arrival, found the gates to Culann's land locked. Jumping the wall, Sétanta was set upon by a vicious hound guarding Culann's land. The hound lunged, but Sétanta's reactions were quick. Grabbing his hurley, he drove a sliotar down the hounds throat, killing it instantly.
Wracked with remorse, Sétanta offered to take the place of Culann;s hound. From that day forth he became known as Cú Chulainn