perhaps you mean cuchalainn? born setanta, a great athlete and warrior, he killed the great guard dog of the king of ulster, culann, by hitting a ball into its throat. he then took on the duties of the guard dog himself, taking the name C� Chulainn, the hound of culann.

AnswerCuchulainn was one of the great warrior heros of Ireland. He was born setanta and gained his new name when he and his uncle King Conchobar Mac Neassa went to visit Chulainn setanta arrived late after the rest had gone in and chulainn had already released his hound when the dog attacked setanta he killed it. To make up for what he had done to chulainn he became the guard for chulainn. Until chulainn could train another hound hence the name change to Cuchaulainn.If you want to know more of Cuchulainn I would suggest reading The Tain. As relates the full history of Cuchulainn.