| # | Name | Origin | Meaning | Gender | |
|---|---|---|---|---|---|
| 141 | Cassian | Welsh | Curly-headed. | M | |
| 142 | Cassidy | Welsh | Curly-headed. | M | |
| 143 | Casswallawn | Welsh | Legendary son of Beli. | M | |
| 144 | Caswallon | Welsh | Legendary son of Beli. | M | |
| 145 | Caw | Welsh | Full of joy. | M | |
| 146 | Cawrdav | Welsh | Legendary son of Caradawg. | M | |
| 147 | Ccri | Welsh | Loved one. | M | |
| 148 | Cedric | Welsh | War leader; gift of splendor. | M | |
| 149 | Cedrick | Welsh | Variant of Cedric: War leader; gift of splendor. | M | |
| 150 | Cedrik | Welsh | Gift of splendor. | M | |
| 151 | Cedrych | Welsh | Variant of Cedric: War leader; gift of splendor. | M | |
| 152 | Ceithin | Welsh | Legendary uncle of Lugh. | M | |
| 153 | Cerdic | Welsh | Cherished. | M | |
| 154 | Ceredig | Welsh | Variant of Cerdic: Cherished. | M | |
| 155 | Ceretic | Welsh | Variant of Cerdic: Cherished. | M | |
| 156 | CIyde | Welsh | Loud voiced. | M | |
| 157 | CIywd | Welsh | Loud voiced. | M | |
| 158 | Cledwyn | Welsh | Rough; blessed. | M | |
| 159 | Clud | Welsh | Lame. | M | |
| 160 | Clust | Welsh | Legendary son of Clustveinydd. | M | |