| Ni Hil | Post Metal | Araba | |
| NoisAlive | Heavy Metal | Nafarroa | |
| Nox Larvae | Death/Thrash Metal | Bizkaia | |
| Nukore | Nu Metal | Araba | |
| Nulled | Metalcore | Araba | |
| Numen | Black Metal | Gipuzkoa | |
| Nunk | Metalcore | Gipuzkoa | |
| Nx | Rock/Metal | Nafarroa | |
| Obstetra | Death/Grindcore | Bizkaia | |
| Odem | Alt Metal | Bizkaia | |
| Odolean | Black Metal | Nafarroa Beherea | |
| Oh, Leader! | Math/Prog Metal | Gipuzkoa | |
| Orihen | Rock/Metal | Bizkaia | |
| Orion Child | Power Metal | Bizkaia | |
| Ossyris | Power Metal | Bizkaia | |
| Ostots | Black Metal | Bizkaia | |
| Our Natural Killer (Onk) | Metalcore/Hardcore | Bizkaia | |
| Overloud | Hard Rock | Gipuzkoa | |
| Oxida | Death'n'roll | Gipuzkoa | |
| Oxido | Heavy Metal | Nafarroa | |
| Ozki | Doom/Sludge Metal | Gipuzkoa | |
| Patxa | Heavy Metal | Bizkaia | |
| Patxi Luque | Hard & Heavy | Gipuzkoa | |
| Pestilength | Black/Death/Doom Metal | Bizkaia | |
| Pi L.T. | Alt Rock/Metal | Bizkaia | |
| Prophetic Scourge | Death Metal | Lapurdi | |
| Psilocybe | Thrashcore | Araba | |
| Punto Muerto | Heavy/Thrash Metal | Gipuzkoa | |
| Putzu Beltzean | Heavy Metal | Gipuzkoa | |
| Quaoar | Prog Rock/Metal | Bizkaia |