Fergus mac Róich

Fergus mac Róich (son of Ró-ech or "great horse"; also mac Róig, mac Rossa) is a character of the Ulster Cycle of Irish mythology. Formerly the king of Ulster, he is tricked out of the kingship and betrayed by Conchobar mac Nessa, and becomes the ally and lover of Conchobar's enemy queen Medb of Connacht, and joins her expedition against Ulster in the Táin Bó Cúailnge. The name Fergus (later Irish Fearghus) means "man-strength" or "virility", and Fergus is described as being of enormous size and sexual potency. This leads him into many a precarious situation as in the story of the Táin Bó Flidhais.

King of Ulster

Fergus becomes king of Ulster after his predecessor, Eochaid Sálbuide, is killed, along with the High King Fachtna Fáthach, by Eochu Feidlech in the Battle of Leitir Ruad. While king, he desires Eochaid Sálbuide's daughter Ness, but she will only consent to marry him if he allows her son Conchobar to be king for a year, so his sons will be the sons of a king. The nobles of Ulster reassure him that the boy will be king in name only, so Fergus agrees, but Conchobar, with his mother's help, rules so wisely that the nobles make him king permanently in Fergus's place. Fergus remains Conchobar's loyal retainer, and becomes the foster-father of Conchobar's eldest son Cormac Cond Longas and nephew Cúchulainn.