| Connor | Man | Irish Names |
| Conor | Man | Irish Names |
| Conway | Man | Irish Names |
| Corcoran | Unisex | Irish Names |
| Corentine | Unisex | Irish Names |
| Corey | Unisex | Irish Names |
| Cormac | Man | Irish Names |
| Corrigan | Unisex | Irish Names |
| Corwin | Unisex | Irish Names |
| Cory | Unisex | Irish Names |
| Coventina | Woman | Irish Names |
| Crevan | Man | Irish Names |
| Cunningham | Man | Irish Names |
| Curran | Man | Irish Names |
| Curry | Man | Irish Names |