[Ir., chafer-tongued, given to backbiting]. Also
[Ir., chafer, dung-beetle of Ulster]; also
, a son of Lugaid mac Casrubae;
An Ulster warrior noted for his rancorous disposition; he shares with Briccriu the role of the Thersites of the Ulster Cycle. Though he was an effective warrior, his companionship was often shunned by comrades in battle. He was given the loan of Celtchar's lance, Lúin, but it was later found discarded. In the Deirdre story, Dubthach assists Fergus mac Roich in his attempts to take revenge on Conchobar for the killings of the sons of Uisnech. In the Táin Bó Cuailnge [Cattle Raid of Cooley], Dubthach kills Maine (8), Conchobar's son; Fiachna, the son of Conchobar's daughter Fedelm Noíchrothach; and all the girls of Emain Macha. Later he goes into exile in Connacht with Cormac and Fergus mac Róich. He also appears in Togail Bruidne Da Derga [The Destruction of Da Derga's Hostel] and can be seen causing discord in Fled Bricrenn [Briccriu's Feast].