| # | Name | Origin | Meaning | Gender | |
|---|---|---|---|---|---|
| 421 | Kevyn | Welsh | From the ridge. | M | |
| 422 | Kian | Welsh | Legendary father of Lugh. | M | |
| 423 | Kilydd | Welsh | Legendary son of Kelyddon. | M | |
| 424 | Kim | Welsh | Diminutive of Kimball: Chief of war. Leader. | M | |
| 425 | Kimball | Welsh | Warrior chief. | M | |
| 426 | Kimble | Welsh | Warrior chief. | M | |
| 427 | Kraig | Welsh | Variant of Craig: Rock. | M | |
| 428 | Kyledyr | Welsh | Legendary son of Nwython. | M | |
| 429 | Kynan | Welsh | Chief. | M | |
| 430 | KyndMryn | Welsh | Legendary son of Ermid. | M | |
| 431 | Kynedyr | Welsh | Legendary son of Hetwn. | M | |
| 432 | Kynlas | Welsh | Legendary son of Kynan. | M | |
| 433 | Kynon | Welsh | Legendary son of CIydno. | M | |
| 434 | Kynwal | Welsh | Legendary son of Caw. | M | |
| 435 | Kynwyl | Welsh | Name of a saint. | M | |
| 436 | Kywrkh | Welsh | Legendary son of Cleddyv. | M | |
| 437 | Leoline | Welsh | Variant of Llewellyn: Leader. Lion-like. | M | |
| 438 | Lew | Welsh | Variant of Llewellyn: Leader. Lion-like. | M | |
| 439 | Lewellyn | Welsh | Lionlike. Leader. | M | |
| 440 | Llacheu | Welsh | Legendary son of Aahur. | M | |