- Merthyr
- Merthyr Cynog
- Merthyr Mawr
- Merthyr Tydfil
- Meyllteyrn
- Middle Mill
- Milford Haven
- Minera
- Minffordd
- Minwear
- Mitchel Troy
- Mochdre
- Moel-tryfan
- Moelfre
- Monington
- Monknash
- Monkswood
- Morfa
- Morfa Bach
- Morfa Nefyn
- Morriston
- Morvil
- Mostyn
- Mountain Ash
- Moylgrove
- Myddfai
- Mydroilin
- Mynachlogddu
- Mynyddislwyn
- Marshfield