| Malevolic | Black Metal | Bizkaia | |
| Mandrágora Negra | Heavy/Power Metal | Gipuzkoa | |
| MDMA | Brutal Death Metal | Bizkaia | |
| MDO | Metal/Hardcore | Nafarroa | |
| Mehatxu | Metal | Araba | |
| Meliora | Hard Rock/Heavy Metal | Gipuzkoa | |
| Melmak | Metal/Sludge/Doom | Bizkaia | |
| Mi Dulce Geisha | Rock/Metal | Bizkaia | |
| Midnight Road | Hard Rock | Bizkaia | |
| Mise en Abyme | Prog Rock/Metal Instrumentala | Gipuzkoa | |
| Mitosia | Rock/Metal | Bizkaia | |
| Moira Krank | Alt Rock/Metal | Lapurdi | |
| Molykote | Death Metal | Bizkaia | |
| Ms. Missery | Alt Rock/Metal | Bizkaia | |
| Muküru | Metal | Gipuzkoa | |
| Mundo Rata | Thrash/Death Metal | Araba | |
| Mutilated Judge | Grindcore | Bizkaia | |
| My Sweet Torment | Black/Death Metal | Bizkaia | |
| NaizPresidente | Metal/Hardcore/Stoner | Gipuzkoa | |
| 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 | |
| Nexus Time | Alt Metal | Gipuzkoa | |
| Ni Hil | Post Metal | Araba | |
| NoisAlive | Heavy Metal | Nafarroa | |
| Nox Larvae | Death/Thrash Metal | Bizkaia | |
| Nukore | Nu Metal | Araba |