| Mehatxu | Metal | Araba | |
| Meliora | Hard Rock/Heavy Metal | Gipuzkoa | |
| Melmak | Metal/Sludge/Doom | Bizkaia | |
| Meriur | Metalcore | Nafarroa | |
| Mi Dulce Geisha | Rock/Metal | Bizkaia | |
| Midnight Road | Hard Rock | Bizkaia | |
| Mise en Abyme | Prog Metal | Gipuzkoa | |
| Mitosia | Rock/Metal | Bizkaia | |
| Mosh | Metal/Rock | Nafarroa | |
| Mørgue | Thrashcore | Gipuzkoa | |
| Ms. Missery | Alt rock/metal | Bizkaia | |
| Mundo Rata | Thrash/Death Metal | Araba | |
| Mutilated Judge | Grindcore | Bizkaia | |
| My Sweet Torment | Black/Death Metal | Bizkaia | |
| Nakkiga | Pagan Black Metal | Araba | |
| NameOff | Rock/Metal/Hardcore | Araba | |
| Neila | Post Metal | Bizkaia | |
| Nekrocake | Death Metal | Bizkaia | |
| Neriva | Metal | Bizkaia | |
| Nessun Dorma | Metal | Bizkaia | |
| Ni Hil | Post Metal | Araba | |
| Nihilrage | Death Metal | Nafarroa | |
| NoisAlive | Metal | Nafarroa | |
| Nox Larvae | Death/thrash metal | Bizkaia | |
| NTN | Metal | Nafarroa | |
| Nuclear Revenge | Black/Thrash Metal | Araba | |
| Nukore | Nu Metal | Araba | |
| Nulled | Metalcore | Araba | |
| Numen | Black Metal | Gipuzkoa | |
| Nunk | Metalcore | Gipuzkoa |
