| # | Name | Origin | Meaning | Gender | |
|---|---|---|---|---|---|
| 521 | Gwynn | Welsh | Handsome. Son of Nudd. | M | |
| 522 | Gwynne | Welsh | White. | F | |
| 523 | Gwynneth | Welsh | White. Fair. Happiness. Blessed. | F | |
| 524 | Gwyr | Welsh | Pure or from Gower. | M | |
| 525 | Gwystyl | Welsh | Legendary son of Nwython. | M | |
| 526 | Gwythyr | Welsh | Legendary son of Greidyawl. | M | |
| 527 | Hayden | Welsh | Variant of Haydn: Fire. Derived from the Celtic name Aidan. | M | |
| 528 | Haydn | Welsh | Fire. Derived from the Celtic name Aidan. | M | |
| 529 | Haydon | Welsh | Variant of Haydn: Fire. Derived from the Celtic name Aidan. | M | |
| 530 | Heilyn | Welsh | Legendary son of Gwynn. | M | |
| 531 | Hen Beddestyr | Welsh | Legendary son of Erim. | M | |
| 532 | Hen Was | Welsh | Old servant. | M | |
| 533 | Hen Wyneb | Welsh | Old face. | M | |
| 534 | Heulwen | Welsh | Sunshine. | F | |
| 535 | Howel | Welsh | Variant of Hywel: Eminent. Attentive. | M | |
| 536 | Howell | Welsh | Variant of Hywel: Eminent. Attentive. | M | |
| 537 | Hu | Welsh | Welsh form of Hugh 'intelligent'. | M | |
| 538 | Huabwy | Welsh | Legendary son of Gwryon. | M | |
| 539 | Huarwar | Welsh | Legendary son of Avlawn. | M | |
| 540 | Hueil | Welsh | Legendary son of Caw. | M | |