| Cibil | Variant Of Sibyl: In Greek Mythology A Name For Prophetess Or Fortune-Teller. | Female |
| Cindel | Abbreviation Of Cynthia And Lucinda. | Female |
| Cingeswell | Lives At The King's Spring | Male |
| Cinnfhail | From The Head Of The Cliff | Male |
| Cinwell | Lives At The King's Spring | Male |
| Circehyll | Lives At The Church Hill | Male |
| Claribel | Bright | Female |
| Cnidel | Name Of A King | Male |
| Coatl | Snake | Male |
| Codell | Helpful. | Male |
| Coireail | Lordly | Male |
| Conal | High: Mighty. | Male |
| Conall | Myth Name (Ulster Chieftain) | Male |
| Connal | High: Mighty. | Male |
| Connell | Strong In Battle | Male |
| Coral | From The Coral Of The Sea | Female |
| Cordell | Cordmaker. | Male |
| Costel | Meaning Unknown | Male |
| Coszcatl | Jewel | Female |
| Covell | Lives At The Cave Slope | Male |
| Covyll | Lives At The Cave Slope | Male |
| Coyotl | Coyote | Male |
| Cozamalotl | Rainbow | Female |
| Crandall | From The Crane Valley | Male |
| Crandell | From The Crane Valley | Male |