| Chelsea | From the landing place for chalk; Port; Port of Ships; Seaport. Place name: a London district. |
| Cindy | Dimunitive of Cynthia, Lucinda, and Cinderella.; Derives From Cynthia; Eart; From the name CYNTHIA |
| CIyde | A name meaning a river or stream. |
| CIywd | A name of ancient Welsh origin. |
| Claire | Bright; Clear, Bright; Form of Clara, meaning 'famously bright'; From the name CLARA; Variant of Clara: From the feminine form of the Latin adjective 'clarus' meaning bright or clear. Also distinguished. Famous bearer: Twelfth century St Clare (or Clara) |
| Cledwyn | Rough; blessed. |
| Clud | A variant of the name Claude. |
| Cnychwr | Legendary son of Nes. |
| Coch | Legendary son of Caw. |
| Coed | Dwells in the woods. |
| Colwin | Variant of Colwyn: Name of a river in Wales. |
| Colwyn | A river in Wales. |
| Colywnn | Variant of Colwyn: Name of a river in Wales. |
| Connah | A variant meaning a wise leader. |
| Conwy | Variant of Conway: Holy river. Place-name and surname. |
| Conyn | Legendary son of Caw 'wise'. |
| Cora | Heart, Maiden; From 'kore' meaning girl or maiden. Famous bearers: Persephone used the title Kore.; Maiden; Seething pool; A young maiden |
| Corey | Chosen; God's Servant; Hill hollow.; From the hollow; of the churning waters; Ravine.; From the round hill or hollow.; Seething pool; Variant of Cory meaning variously - From the round hill: seething pool: ravine |
| Corsen | One who hails from the marsh. |
| Craddock | Affection; beloved. |
| Cradoe | A name meaning a rocky hill. |
| Cragen | Welsh name meaning a crag. |
| Creiddylad | Jewel of the sea. |
| Crist | A follower of the Christian faith. |
| Crwys | Welsh word for the cross. |
| Cubert | Legendary son of Daere. |
| Culvanawd | Legendary son of GwIyon. |
| Custenhin | Legendary father of Erbin. |
| Cwrig | A name meaning born of fire. |
| Cymreiges | A name meaning a Welsh woman. |
| Cymry | A name meaning the Welsh people. |
| Cynan | A name meaning a great chief. |
| Cynbal | A name meaning a musical cymbal. |
| Cynbel | A name meaning a wise leader. |
| Cynddelw | A name meaning a noble image. |
| Cyndeyrn | A name meaning a chief lord. |
| Cystenian | Steady; stable. |
| Cystennin | A Welsh form of the name Constantine. |
| Daere | One who is very beloved. |
| Dalldav | Legendary son of Cunyn Cov. |