| # | Name | Origin | Meaning | Gender | |
|---|---|---|---|---|---|
| 301 | Costa | Greek | Steady; stable. | M | |
| 302 | Cottus | Greek | A Titan. | M | |
| 303 | Creon | Greek | Prince. Jocasta's brother. | M | |
| 304 | Cretien | Greek | Christian. | M | |
| 305 | Cristoforo | Greek | Christ bearer. | M | |
| 306 | Cristophe | Greek | Christ bearer. | M | |
| 307 | Cronus | Greek | A Titan. | M | |
| 308 | Ctesippus | Greek | One of Penelope's suitors. | M | |
| 309 | Cy | Greek | Diminutive of Cyril: Lord, lordly. Famous bearer, the 9th-century missionary Saint Cyril, devised the Cyrillic alphabet used in Slavonic languages. | M | |
| 310 | Cycnus | Greek | Swan. | M | |
| 311 | Cyprian | Greek | From Cyprus. | M | |
| 312 | Cyr | Greek | Lordly. | M | |
| 313 | Cyrano | Greek | From Cyrene (Greek island). | M | |
| 314 | Cyrek | Greek | Lordly. | M | |
| 315 | Cyril | Greek | Lord, lordly. Famous bearer, the 9th-century missionary Saint Cyril, devised the Cyrillic alphabet used in Slavonic languages. | M | |
| 316 | Cyrill | Greek | Master; lord. | M | |
| 317 | Cyrille | Greek | Variant of Cyril: Lord. | M | |
| 318 | Cyrillus | Greek | Variant of Cyril: Lord. | M | |
| 319 | Cyrus | Greek | Enthroned. Cyrus the Great conquered Babylon and founded the Persian Empire. | M | |
| 320 | Cyryl | Greek | Lordly. | M | |