Castus is the name of several early Christians.
1. Bishop of Sicca Venerea (Kef, a proconsular province, near Musti, on the borders of Numidia (the town of Arnobius), spoke twenty-eighth in order in the Synod of Carthage (Sentt . Eusub Cycl. 7).
2. Castus and Emilius were two men who lapsed, and then made renewed confession; mentioned by Cyprian, under Decius, as having suffered some time before (Cyp. Laps. c. 13; Tillemont, 3, 125); and commemorated in the calendar of Carthage, by Bede, etc., on May 22.
3. A bishop, imprisoned along with pope Stephen, A.D. 257 (Anastasius, 1, 1390, ed. Migne; Tillemont, 4:31).
4. A bishop at the Council of Sinuessa, A.D. 303, and of Rome, A.D. 324 (Labbe, Concil. 1, 940,1545).
5. Bishop of Saragossa at the Council of Sardica A.D. 347 (Labbe, Concil. 2, 658, 662, 678).
6. A Donatist bishop of Cella, at the Council of Carthage, A.D. 411 (Labbe, Concil. 2, 1379).
7. A presbyter of Antioch, who, in conjunction with Valerius, Diophantus, and Cyriacus, maintained the cause of Chrysostom and the orthodox clergy against the tyrannical intruder Porphyrius, by whom they were grievously persecuted.
8. Martyred, according to the Hieronymian. Mart., Sept. 4.
9. A martyr at Capuai Oct. 6, according to the martyrologies.
10. Bishop of Porto in the third Roman Synod, A.D. 501; the fourth, A.D. 502; and the sixth, A.D. 504 (Labbe, Concil. 4, 1326, 1334, comp. 1377).