| N A M E | O R I G I N | M E A N I N G |
| Casimire | Polish | Variant of Casimir: Bringer of peace; announcing peace. |
| Casimiro | Polish | Variant of Casimir: Bringer of peace; announcing peace. |
| Casnar | Welsh | Legendary nobleman. |
| Caspar | German | Royal |
| Casper | Persian | treasurer |
| Cass | English | Diminutive of Caspar: Wealthy man. |
| Cassady | Irish | Variant of Cassidy: Intelligent; from Caiside; curly-headed. |
| Cassian | Irish | Curly-headed. |
| Cassidy | Gaelic | clever |
| Cassius | Latin | vain |
| Cassivellaunus | Celtic | From Arthurian legend. |
| Casswallawn | Welsh | Legendary son of Beli. |
| Castel | Spanish | belonging to a castle |
| Caster | English | From the Roman camp. |
| Castimer | Polish | Variant of Casimir: Bringer of peace; announcing peace. |
| Castle | English | Castle. |
| Castor | Greek | Beaver. Brother of Helen. |
| Caswallan | Celtic | From Arthurian legend. |
| Caswallon | Welsh | Legendary son of Beli. |
| Cat | Scottish | Catlike. |
| Cater | English | One who caters. |
| Cathair | Celtic | Fighter. |
| Cathal | Celtic/Gaelic | Mighty battle |
| Cathall | Irish | Ready for war. |
| Cathaoir | Celtic | Fighter. |
| Cathaoirmore | Gaelic | Great warrior. |
| Cathmor | Gaelic | Great warrior. |
| Cathmore | Gaelic | Great warrior. |
| Cato | Latin | sagacious, wise one |
| Caton | Spanish | knowledgable, wise |
