| Calvagh | Man | Irish Names |
| Caoimhe | Woman | Irish Names |
| Caoimhín | Man | Irish Names |
| Caolan | Man | Irish Names |
| Carey | Unisex | Irish Names |
| Cargan | Man | Irish Names |
| Carlin | Unisex | Irish Names |
| Carlow | Man | Irish Names |
| Carr | Man | Irish Names |
| Carrigan | Unisex | Irish Names |
| Casey | Unisex | Irish Names |
| Cashel | Man | Irish Names |
| Cassidy | Unisex | Irish Names |
| Cathair | Man | Irish Names |
| Cathal | Man | Irish Names |
| Cathán | Man | Irish Names |
| Cathleen | Woman | Irish Names |
| Cavan | Man | Irish Names |
| Cayleen | Woman | Irish Names |
| Ceallach | Man | Irish Names |