| Cleto | | KLE-to (Italian, Spanish) | Italian, Spanish, Portuguese | |
| CloÉ | | klo-E (French) | Portuguese, French | |
| Clotilde | | klo-TEELD (French) | French, Italian, Portuguese, Spanish | |
| ConstÂNcia | | - | Portuguese | |
| ConstanÇA | | - | Portuguese | |
| CornÉLio | | - | Portuguese | |
| Cosme | | - | Portuguese, French | |
| CristÓVÃO | | - | Portuguese | |
| Cristiana | | kree-STYAH-nah (Italian) | Italian, Portuguese | |
| Cristiano | | kree-STYAH-no (Italian), kreesh-TYA-noo (Portuguese) | Italian, Portuguese | |
| Cristina | | kree-STEE-nah (Italian, Spanish) | Italian, Spanish, Portuguese, Romanian | |
| Cruz | | KROOTH (Spanish), KROOS (Latin American Spanish), KROOSH (Portuguese) | Spanish, Portuguese | |
| CustÓDia | | - | Portuguese | |
| CustÓDio | | - | Portuguese | |
| DŨNg | | - | Vietnamese | |