| Name | Meaning | Gender | Origin |
|---|
| Mercia | Border people | Female | English |
| Meredith | Great lord | Female | Welsh |
| Merrick | Moor | Male | Welsh |
| Mervin | Uncertain, possibly eminent marrow | Male | Welsh |
| Mervyn | Uncertain, possibly eminent marrow | Male | Welsh |
| Mona | Little noble one | Female | Gaelic |
| Morgan | Uncertain, perhaps bright sea | Female | Welsh |
| Morgana | Uncertain, perhaps bright sea | Female | Welsh |
| Morgen | Sea-born | Female | Welsh |
| Morven | Lives By The Sea | Male | English |
| Morwen | Maid | Female | Welsh |
| Morwenna | Maid | Female | Welsh |
| Mostyn | Moss enclosure | Unisex | English |
| Myfanwy | My little lovely one | Female | Welsh |
| Nerys | Lady | Female | Welsh |
| Nia | Radiance | Female | Gaelic |
| Nimue | The Lady Of The Lake | Female | Welsh |
| Nye | Island | Male | Welsh |
| Olwen | White footprint | Female | Welsh |
| Owen | Well born, yew born | Male | Gaelic |
| Owena | Well born, yew born | Female | Gaelic |
| Parry | Son of Harry | Male | Welsh |
| Penn | Hill | Male | English |
| Price | Son of Rhys | Male | Welsh |
| Reece | Enthusiasm | Male | Welsh |
| Reese | Enthusiasm | Male | Welsh |
| Ren | Water lily | Female | Japanese |
| Renfrew | Dwells Near The Still River | Male | Welsh |
| Rhett | Advice, counsel | Male | English |
| Rhian | Maiden | Female | Welsh |