| # | Name | Origin | Meaning | Gender | |
|---|---|---|---|---|---|
| 261 | Conway | Gaelic | Hound of the plain. | M | |
| 262 | Corcoran | Gaelic | Reddish skinned. | M | |
| 263 | Corcurachan | Gaelic | Reddish skinned. | M | |
| 264 | Corey | Gaelic | Ravine. | M | |
| 265 | Cori | Gaelic | Ravine. | M | |
| 266 | Cormac | Gaelic | Charioteer. Famous bearer, a legendary third century Irish king. | M | |
| 267 | Cormack | Gaelic | Charioteer. | M | |
| 268 | Cormick | Gaelic | Charioteer. | M | |
| 269 | Corwin | Gaelic | From beyond the hill. | M | |
| 270 | Corwyn | Gaelic | From beyond the hill. | M | |
| 271 | Coty | Gaelic | Ravine. | M | |
| 272 | Cowan | Gaelic | Dwells by the hillside hollow. | M | |
| 273 | Coyle | Gaelic | Searches for battle. | M | |
| 274 | Craig | Gaelic | Dwells at the Crag. | M | |
| 275 | Creag | Gaelic | Dwells at the Crag. | M | |
| 276 | Criostoir | Gaelic | Christ bearer. | M | |
| 277 | Crisdean | Gaelic | Christ bearer. | M | |
| 278 | Cronan | Gaelic | Dark brown. | M | |
| 279 | Cuilean | Gaelic | Cub. | M | |
| 280 | Cuini | Gaelic | Queen. | F | |