| Cleophas | | KLEE-ə-fəs (English) | Biblical | |
| Cletis | | KLEE-tis | English (Rare) | |
| 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 | |
| Clopas | | KLO-pəs (English) | Biblical | |
| Clothildis | | - | Ancient Germanic (Latinized) | |
| Clotho | | - | Greek Mythology (Latinized) | |
| Clotilde | | klo-TEELD (French) | French, Italian, Portuguese, Spanish | |