Cathirius is the name of several early Christians:
1. Bishop of the Cimmerian Bosporus, present at the Council of Nice (Tillemont, 6:643; Labbe, Concil. 2, 54).
2. Bishop of Arpona, at the heretical Council of Sardica, A.D. 347 (Labbe, Concil. 2, 711).
3. Bishop at the Council of Saragossa A.D. 381. In this and the previous case the name is spelled Catherius; the last name with a variation, Cartherius. 1 In Gams's Series Lipiscoporum the name of the bishop of Arpona is given as Carterius.