Often with the patronymic mac Uithechair, mac Uthechar, mac Cuthechair, mac Uthidir, etc.; sometimes Celtchair Mór [the Great]. A leading figure in the Ulster Cycle, often included in catalogues of the most important fighters. Several stories describe him as huge and grey. He may boast of his killing, but in Scéla Mucce meic Da Thó [The Story of Mac Da Thó's Pig], Celtchair is humiliated when the warrior Cet claims to have emasculated him in a previous encounter. He is the usual possessor of the lance known as Lúin, whose lust for blood was so great that if it were not used it had to be dipped into a cauldron containing black fluid or poison or its shaft would break into flames. He killed Blaí Briugu for sleeping with his wife, and later cleared the country of pests, including (with the help of his daughter Niam (2) Conganchnes mac Dedad and the black hound Dóelchu. One drop of the slain hound's blood ran along Celtchair's spear and went through his body.
See Kuno Meyer (ed.), Death Tales of Ulster Heroes (Dublin, 1906);repr. in T. P. Cross and C. H. Slover (eds.), Ancient Irish Tales (New York, 1936, 1969), 340–3.See also ‘Celtchair mac Cuthechair’, in M. E. Dobbs, Side-Lights on the Táin Age (Dundalk, 1917);Kim McCone, ‘Aided Cheltchair maic Uthechair. Hounds, Heroes, and Hospitallers in Early Irish Myth and Story’, Ériu, 35 (1984), 1–30.