- Moyglass
- Moylough
- Moyrus
- Muckanagh
- Muckanaghkillew
- Muckareaghederdauhaulia
- Muckrush
- Mullagh
- Mullaghglass
- Mulroog
- Muskerry Island
- Mutton Island
- Mutton Island
- Mweenish Island
- Mweenish Island
- Mweenisharan
- Magurk
- Manorhamilton
- Mayo
- Meenkeeragh
- Meenymore
- Moher
- Mohill
- Moneyduff
- Morerah
- Mullagh
- Mullaghboy
- Mullaghdoo
- Mullaghgarve
- Mullanadarragh