| Clementina | | kle-men-TEE-nah (Italian, Spanish), klə-mən-TEE-nə (Portuguese) | Italian, Spanish, Portuguese | |
| Clementius | | - | Late Roman | |
| Cleon | | - | Ancient Greek (Latinized) | |
| Cleopatra | | klee-ə-PAT-rə (English) | Ancient Greek (Latinized) | |
| Cleto | | KLE-to (Italian, Spanish) | Italian, Spanish, Portuguese | |
| Climacus | | - | Late Roman | |
| Climent | | klee-MENT | Catalan | |
| Clio | | KLEE-o (Italian) | Greek Mythology (Latinized), Italian | |
| Clitus | | - | Ancient Greek (Latinized) | |
| Clodovicus | | - | Ancient Germanic (Latinized) | |
| Cloe | | - | Spanish, Italian | |
| Cloelia | | - | Ancient Roman | |
| Cloelius | | - | Ancient Roman | |
| Clothildis | | - | Ancient Germanic (Latinized) | |
| Clotilde | | klo-TEELD (French) | French, Italian, Portuguese, Spanish | |