| Cathall | A name meaning mighty in battle. |
| Catharine | Form of the Greek Catherine meaning pure |
| Cathasach | A name meaning the vigilant one. |
| Cathleen | Form of the Greek Catherine meaning pure |
| Cathmor | A Gaelic name meaning great battle. |
| Cathmore | A name meaning great warrior. |
| Catlee | A meadow of wild cats. |
| Catlin | Variant of Katherine meaning pure |
| Catline | Variant of Katherine meaning pure |
| Catlyn | Variant of Katherine meaning pure |
| Catriona | Variant of Katherine meaning pure |
| Cattee | A playful feline soul. |
| Caulan | Variant of Caelan: Powerful warrior. |
| Cavan | A name meaning handsome or fair. |
| Cavana | One who lives in the forest. |
| Cayce | Variant of Casey: Observant; alert; vigorous. |
| Caycee | A vigilant and watchful person. |
| Caycey | Variant of Casey: Observant; alert; vigorous. |
| Caydence | A rhythmic flow of musical sounds. |
| Ceallach | A bright and warlike warrior. |
| Ceallachan | A small and brave little head. |
| Cearnach | A name meaning a victorious man. |
| Cein | A name meaning jewel or precious gem. |
| Ceire | Derived from the word for dark. |
| Celsus | Name of a saint |
| Cerdwin | the mother goddess |
| Channe | A name meaning a gracious gift. |
| Chiara | Dark. Feminine of Ciaran. |
| Chrissa | Abbreviation of Christine. Follower of Christ. |
| Chrissie | Abbreviation of Christine. Follower of Christ. |
| Chrissy | Abbreviation of Christine. Follower of Christ. |
| Christi | Abbreviation of Christine. Follower of Christ. |
| Christie | Abbreviation of Christine. Follower of Christ. |
| Cian | An ancient name meaning ancient. |
| Cianan | A name meaning ancient or old. |
| Ciannait | A name meaning little ancient. |
| Ciar | A name meaning dark or black. |
| Ciara | Saint or Dark. Feminine of Ciaran. |
| Ciardha | Variant of Ciaran: Black-haired. |
| Ciarrai | From the darkhaired people. |