| # | Name | Origin | Meaning | Gender | |
|---|---|---|---|---|---|
| 621 | Ciro | Greek | Sun or lordly. | M | |
| 622 | Claas | Greek | People's victory. | M | |
| 623 | Claus | Greek | People's victory. | M | |
| 624 | Clea | Greek | Abbreviation of Clotilde and Cleopatra. | F | |
| 625 | Clematis | Greek | Flower name. | F | |
| 626 | Cleo | Greek | A diminutive of Cleopatra and Clotilde, meaning famed. Famous bearer: 20th century British jazz singer Cleo Laine. | F | |
| 627 | Cleo | Greek | Illustrious. | M | |
| 628 | Cleobis | Greek | Son of a priestess. | M | |
| 629 | Cleon | Greek | Famed; famous; illustrious. | M | |
| 630 | Cleone | Greek | The mythological daughter of a river god. | F | |
| 631 | Cleopatra | Greek | Her father's fame; Glory of her father. Egyptian Queen immortalized by Shakespeare in Antony and Cleopatra'. | F | |
| 632 | Cleta | Greek | Illustrious. | F | |
| 633 | Cletus | Greek | Variant of Anakletos: Calling forth; summoned. | M | |
| 634 | Cleytus | Greek | Illustrious. | M | |
| 635 | Cliantha | Greek | Glory. | F | |
| 636 | Clianthe | Greek | Glory. | F | |
| 637 | Clio | Greek | Celebrate. Abbreviation of Clotilde and Cleopatra. Clio was the Mythological Muse of historic poetry. | F | |
| 638 | Cloria | Greek | Goddess of spring. | F | |
| 639 | Cloris | Greek | Blooming. Mythological goddess of flowers or spring. | F | |
| 640 | Clotho | Greek | A Fate. | F | |