Ferdia, son of Damán, son of Dáire, of the Fir Domnann, is a warrior of Connacht in the Ulster Cycle of Irish mythology. In the Táin Bó Cúailnge, Ferdia finds himself on opposite sides to his best friend and foster-brother Cúchulainn who may also have been his lover, with whom he had trained in arms under the renowned warrior woman Scáthach. He and Cúchulainn are equal in all martial feats, with two exceptions: the Gáe Bulg, a barbed spear which Scáthach has taught only Cúchulainn to use; and Ferdia's horny skin, which no weapon can pierce.