[Ir., white horn].
Queen Medb's white bull in Táin Bó Cuailnge [Cattle Raid of Cooley], also known as the White Bull of Connacht and as Whitehorn. According to a foretale to the epic, Finnbennach was originally a man named Rucht, swineherd to Ochall Ochne, who quarrelled with Friuch, swineherd of Bodb Derg. Their dispute was so bitter it survived their transformation into different forms: as ravens, water-beasts, stags, dragons, champions, water-worms, and finally as bulls. As a water-worm Rucht advised Medb to marry Ailill; he was then swallowed by a cow and was begat as Finnbennach. But as he thought it unseemly to be born into the herd of a woman, he had himself born into the herd of Ailill. In maturity, Finnbennach's contest with Donn Cuailnge, the Brown Bull of Ulster, is central to the action of the epic; Finnbennach is eventually defeated, but not without severely wounding Donn Cuailnge.