| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Claritia | - | Late Roman | ||
| Clarus | - | Late Roman | ||
| Clemens | KLE-mens (German) | German, Dutch, Swedish, Norwegian, Danish, Late Roman | ||
| Clementia | - | Late Roman | ||
| Clementius | - | Late Roman | ||
| Climacus | - | Late Roman | ||
| Columba | ko-LOOM-ba (Late Roman), kə-LUM-bə (English) | Late Roman | ||
| Columbanus | - | Late Roman | ||
| Constans | - | Late Roman | ||
| Constantia | - | Late Roman | ||
| Constantina | - | Late Roman | ||
| Constantinus | - | Late Roman | ||
| Constantius | - | Late Roman | ||
| Corbinianus | - | Late Roman | ||
| Corona | - | Late Roman, Italian, Spanish |