| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Clemens | KLE-mens (German) | German, Dutch, Swedish, Norwegian, Danish, Late Roman | ||
| Clementia | - | Late Roman | ||
| Clementius | - | Late Roman | ||
| Climacus | - | Late Roman | ||
| Cloelia | - | Ancient Roman | ||
| Cloelius | - | Ancient Roman | ||
| Cnaeus | - | Ancient Roman | ||
| Columba | ko-LOOM-ba (Late Roman), kə-LUM-bə (English) | Late Roman | ||
| Columbanus | - | Late Roman | ||
| Concordia | kən-KAWR-dee-ə (English) | Roman Mythology | ||
| ConstanȚA | - | Romanian | ||
| Constans | - | Late Roman | ||
| Constantia | - | Late Roman | ||
| Constantin | kon-stahn-TEEN (Romanian), kawn-stawn-TEN (French) | Romanian, French | ||
| Constantina | - | Late Roman |