| Clarus | | - | Late Roman | |
| Claudia | | KLAW-dee-ə (English), KLOW-dee-ah (German, Dutch), KLOW-dyah (Italian, Spanish, Romanian) | English, German, Dutch, Italian, Spanish, Romanian, Biblical, Ancient Roman | |
| Claudio | | KLOW-dyo | Italian, Spanish | |
| Claudiu | | - | Romanian | |
| Claudius | | KLAW-dee-əs (English) | Ancient Roman | |
| Claus | | KLOWS | German, Danish | |
| Cleisthenes | | KLIES-thə-neez (English) | Ancient Greek (Latinized) | |
| Cleitus | | - | Ancient Greek (Latinized) | |
| Clelia | | - | Italian | |
| Clemens | | KLE-mens (German) | German, Dutch, Swedish, Norwegian, Danish, Late Roman | |
| Clemente | | kle-MEN-te (Italian, Spanish) | Italian, Spanish, Portuguese | |
| Clementia | | - | Late Roman | |
| Clementina | | kle-men-TEE-nah (Italian, Spanish), klə-mən-TEE-nə (Portuguese) | Italian, Spanish, Portuguese | |
| Clementius | | - | Late Roman | |
| Cleon | | - | Ancient Greek (Latinized) | |