Cyclopedia of Biblical, Theological and Ecclesiastical Literature 
(Gr. Γάϊος , i.e. Gaius) is the name of several early Christians, not otherwise noted.
1. Only one Gaius is named among the seventy disciples by Dorotheus, and he is said to have succeeded Timothy in the see of Ephesus. In the Menologyhe is commemorated Nov. 4. This may be the Gaius who is, addressed in the third epistle of John, if we suppose Diotrephes to have held the see when the epistle was written.
2. Caius, bishop of Pergamos, is named in the Apostolical Constitutions (vii, 46).
4. The twenty-third bishop of Jerusalem, and called Gaius in the Chronicon (sub anno 160). 'Only one of these is named in Rufinus.
5. Martyr, of Eumenea, at Apamea, who refused to be reckoned with the Montanist martyrs. In the Roman martyrologies he is commemorated March 10.
6. Arrested with Dionysius of Alexandria, A.D. 250, and confined with him in a desert place of Libya. He is commemorated with Dionysius by the Greeks, Oct. 4, as a deacon and martyr.
7. Priest of Didda, was excommunicated, with the approval of Cyprian (Ep. 28), for receiving the lapsed without penance. He is supposed by Tillemont (iv, 94) to have been one of five schismatics named in epistle 40.
8. Gaius, Fortunatus, and Antus are commemorated, Aug. 28, at Salerno, as patron saints; and are supposed to have been companions of Felix. They are not mentioned in the martyrologies of that day, but the first two are frequently joined in the Hieronymian martyrology e.g. Jan. 19, Feb. 2, March 4.
9. One of the martyrs of Saragossa.
10. Martyr, at Nicomedia, Oct. 12, with twelve soldiers, and commemorated in the Roman martyrologies.
11. One of the forty martyrs of Sebaste. This name is frequently mentioned in the Hieronymian martyrology, and occurs in the Lesser Roman martyrology on April 19 (at Militana) and on Nov. 20 (at Messina). Usuard adds one (at Bononia) Jan. 4, and one drowned March 4.
12. Deacon of Alexandria, who followed Arius, and signed his letter to St. Alexander.
13. Orthodox bishop of Thumis, in Egypt, who assisted at the councils of Tyre, Sardica, and Nice. He had to flee from the Arian persecution, and perhaps appears at the Council of Alexandria in A.D. 362, as bishop of Paretonia, in the Libyan desert.
14. The Arian bishop of Pannonia, who was at the Council of Milan in 335, and at the Council of Rimini in 359, maintained the third confession of Sirmium, and was deposed. Afterwards he was reinstated, and sent on a deputation to Constantius. The Semi-Arians who were deposed at Constantinople in 360 asked the Western churches to hold him excommunicated, which they accordingly did, in 371.
15. A heretic, to whom Augustine writes in 390 his epistle 19, sending him all his books.
16. Supposed Donatist bishop at Carthage; others read Carus.
17. Patriarch of Alexandria. (See Gaianus) (6).
18. Monk. (See Dionysius The Areopagite).