- Monmouth
- Montgomery
- Milton
- Machroes
- Machynys
- Maen-y-groes
- Maerdy
- Maes-bangor
- Maeshafn
- Maesygwartha
- Maiden Wells
- Malltraeth
- Mancot Royal
- Manselfield
- Manson
- Marian
- Marianglas
- Markham
- Mascle Bridge
- Mawdlam
- Melin-y-coed
- Melincourt
- Merlin's Bridge
- Merthyr Tewdrig
- Merthyr Vale
- Michaelston-le-Pit
- Middle Mouse
- Middleton
- Middletown
- Midland Isle