|First reference:||Petrified Lightning|
Cúchulainn is an Irish hero and the son of the gods Lugh and Deichtine.
Cúchulainn is an Irish mythological hero who appears in the stories of the Ulster Cycle, as well as in Scottish and Manx folklore. The son of the god Lugh and Deichtine, sister of the king of Ulster, he was originally named Sétanta, but gained his better-known name as a child after he killed Culann's vicious guard-dog in self-defense, and offered to take its place until a replacement could be reared. At the age of seventeen he defended Ulster single-handedly against the armies of Queen Medb of Connacht in the epic Táin Bó Cúailnge ("The Cattle Raid of Cooley"). It was prophesied that his great deeds would give him everlasting fame, but that his life would be short. He is known for his terrifying battle frenzy or "warp spasm", in which he becomes an unrecognizable monster who knows neither friend nor foe. He fights from his chariot, driven by his loyal charioteer Láeg, and drawn by his horses, Liath Macha and Dub Sainglend.
Caitlin tells Peter a tale about Cúchulainn and a mermaid, Teeval. Cúchulainn finds a mermaid on the beach. He binds her, but lets her go when she promised to give him great strength in battle if he would but look upon her name written in his shield.
- In a deleted scene from Ink, as seen on the Season Four DVD, Samuel tells Lydia the old Irish tale of The Hound of Ulster, who had to eventually kill his brother Ferdiad. Cúchulainn is also known as The Hound of Ulster.