Conall Cernach (modern spelling: Conall Cearnach) is a hero of the Ulaid in the Ulster Cycle of Irish mythology. He is said to have always slept with the head of a Connachtman under his knee. His epithet is normally translated as "victorious" or "triumphant", although it is an obscure word, and some texts struggle to explain it. Alternative meanings include "angular, having corners", "swollen", or "possessing a dish or receptacle".
In the destruction of Da Derga's Hostel, Conall Cernach is described as follows:
"I saw a man there in an ornamented dining compartment, who was the fairest of the warriors of Ireland. A fleecy crimson cloak about him. As white as the snow one of the cheeks on him, as freckled-red as the foxglove the other cheek. One of his two eyes is as blue as a hyacinth, as black as a beetle’s back the other eye. The measure of a reaping basket his bushy tree (of) fair, very blond (hair) that is on him. It strikes the edge of his two hips. It is as fleecy as a tufted ram. Though a sack of bountiful (?) red nuts were poured out over the top of his head, not a nut of them would fall to the ground. A goldhilted sword in his hand. A blood-red shield, dotted with rivets of white metal (tincopper alloy) between plates of gold. A long, three-ridged spear, as thick as an outer yoke (of a miller’s team?) the shaft that is on it."
His father was Amairgin mac Echit and his mother was Findchoem. His parents' marriage was barren, until Findchoem visited a druid and was advised to drink from a certain well. She took a drink from the well, swallowing a worm with it, and became pregnant. Findchoem's brother Cet mac Mágach, a Connachtman, protected his sister until she gave birth to a son, Conall. Druids came to initiate the child into their religion, and prophesied that he would kill more than half of the men of Connacht, and that he would always have a Connachtman's head on his belt. Cet took the child, put him under his heel and tried to break his neck, but only damaged it, leaving Conall with a crooked neck.
Conall would have a fierce rivalry with Cet for the rest of his life. He shamed Cet at a feast at the house of Mac Dá Thó, a hospitaller of Leinster, when the warriors of Connacht and Ulster competed for the champion's portion by boasting of their deeds. Cet reminded all comers how he had bested them in combat, including emasculating Celtchar with his spear. However, just as Cet was about to carve, Conall arrived, and his boasts topped even Cet's. Cet admitted defeat, but claimed that if his brother Anlúan were present, his feats would top even Conall's. Conall responded by tossing him Anlúan's freshly severed head.