| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Catrin | KAT-rin (Welsh), KAHT-reen (German) | Welsh, German | ||
| Cefin | - | Welsh | ||
| Ceinwen | - | Welsh | ||
| Celyn | - | Welsh | ||
| Ceri (1) | KE-ri | Welsh | ||
| Ceri (2) | KE-ri | Welsh | ||
| Ceridwen | ke-RID-wen | Welsh | ||
| Cerridwen | - | Welsh | ||
| Cerridwyn | - | Welsh | ||
| Cerys | - | Welsh | ||
| Cledwyn | - | Welsh | ||
| Colwyn | - | Welsh | ||
| Crystin | - | Welsh | ||
| Culhwch | KEEL-hookh (Welsh) | Welsh, Welsh Mythology | ||
| Cystennin | - | Welsh |