| # | Name | Origin | Meaning | Gender | |
|---|---|---|---|---|---|
| 401 | Jesstin | Welsh | Variant of Justin 'Just; upright; righteous.'. | M | |
| 402 | Jestin | Welsh | Variant of Justin 'Just; upright; righteous.'. | M | |
| 403 | Jeston | Welsh | Variant of Justin 'Just; upright; righteous.'. | M | |
| 404 | Kai | Welsh | Keeper of the keys. Form of Kay. | M | |
| 405 | Kane | Welsh | Beautiful. Popular as a first name in Australia. | M | |
| 406 | Kay | Welsh | Fiery. | M | |
| 407 | Kei | Welsh | Legendary son of Kynyr. | M | |
| 408 | Keith | Welsh | Dwells in the woods. | M | |
| 409 | Kelli | Welsh | From the wood. | M | |
| 410 | Kelyn | Welsh | Legendary son of Caw. | M | |
| 411 | Ken | Welsh | Clear water. | M | |
| 412 | Kendric | Welsh | Royal chieftain. Jehovah has remembered. Surname. | M | |
| 413 | Kendrick | Welsh | Royal chieftain. Surname. | M | |
| 414 | Kendrik | Welsh | Royal chieftain. Surname. | M | |
| 415 | Kendrix | Welsh | Royal chieftain. Surname. | M | |
| 416 | Kenn | Welsh | Clear water. | M | |
| 417 | Kenrick | Welsh | Royal chieftain. Surname. | M | |
| 418 | Kenrik | Welsh | Royal chieftain. Surname. | M | |
| 419 | Kent | Welsh | White. | M | |
| 420 | Kenyon | Welsh | From Ennion's mound. | M | |