| # | Name | Origin | Meaning | Gender | |
|---|---|---|---|---|---|
| 581 | Cosgrove | Irish | Triumphant. | M | |
| 582 | Costello | Irish | Surname. | M | |
| 583 | Coughlan | Irish | Hooded. | M | |
| 584 | Covey | Irish | Hound of the plains. | M | |
| 585 | Cowan | Irish | Valley in a hill; twin. | M | |
| 586 | Cowen | Irish | Twin. | M | |
| 587 | Cowyn | Irish | Twin. | M | |
| 588 | Coyle | Irish | Soldier; leader in battle. | M | |
| 589 | Creedon | Irish | A surname meaning 'Belief; guiding principle.'. | M | |
| 590 | Crevan | Irish | Fox. | M | |
| 591 | Crissa | Irish | Abbreviation of Christine: follower of Christ. | F | |
| 592 | Crissie | Irish | Abbreviation of Christine: follower of Christ. | F | |
| 593 | Crissy | Irish | Abbreviation of Christine: follower of Christ. | F | |
| 594 | Cristie | Irish | Abbreviation of Christine: follower of Christ. | F | |
| 595 | Cristin | Irish | Servant of Christ. | F | |
| 596 | Cristy | Irish | Abbreviation of Christine: follower of Christ. | F | |
| 597 | Crogher | Irish | Loves hounds. | M | |
| 598 | Crohoore | Irish | Loves hounds. | M | |
| 599 | Cronan | Irish | Little dark one. | M | |
| 600 | Crowley | Irish | Hunch backed. | M | |