| # | Name | Origin | Meaning | Gender | |
|---|---|---|---|---|---|
| 521 | NewIyn | Welsh | Dwells near the new pool. | M | |
| 522 | Newlin | Welsh | Dwells near the new pool. | M | |
| 523 | NewyddIlyn | Welsh | Dwells near the new pool. | M | |
| 524 | Ninian | Welsh | St. Ninian was a 5th century bishop sent to Scotland to convert the Picts to Christianity. | M | |
| 525 | Nissyen | Welsh | Legendary son of Eurosswydd. | M | |
| 526 | Nye | Welsh | Diminutive of Aneurin: Uncertain origin, but may be derived from the Latin Honorius meaning man of honour, or from the Welsh eur meaning gold. | M | |
| 527 | Nynnyaw | Welsh | Legendary son of Beli. | M | |
| 528 | Odgar | Welsh | Legendary son of Aedd. | M | |
| 529 | Ofydd | Welsh | Welsh form of Ovid 'a Roman poet'. | M | |
| 530 | Ol | Welsh | Legendary son of Olwydd. | M | |
| 531 | Olwydd | Welsh | Tracker. | M | |
| 532 | Ondyaw | Welsh | Legendary son of a French Duke. | M | |
| 533 | Oswallt | Welsh | Welsh form of Oswald 'strength from God'. | M | |
| 534 | Owain | Welsh | Young warrior. | M | |
| 535 | Owein | Welsh | Young warrior. | M | |
| 536 | Owen | Welsh | Young warrior. Also can be a variant of Eugene: Well-born. | M | |
| 537 | Owin | Welsh | Young warrior. | M | |
| 538 | Owyn | Welsh | Young warrior. | M | |
| 539 | Owynn | Welsh | Wellborn. Form of Ewan. | M | |
| 540 | Padrig | Welsh | Welsh form of Patrick 'noble'. | M | |