| Sepulchral | Death Metal | Bizkaia | |
| Sevicia | Metal | Bizkaia | |
| Shallow Waters | Post Black Metal | Gipuzkoa | |
| Shintra | Post-Metal | Bizkaia | |
| Sinmas | Thrashcore | Bizkaia | |
| Sinner Rage | Heavy Metal | Araba | |
| Sinpekado | Thrashcore | Bizkaia | |
| Sixmika | Groove Metal | Araba | |
| Skin Tortured | Death Metal | Bizkaia | |
| Smog | Metalcore | Nafarroa | |
| Soa | Death/thrash metal | Gipuzkoa | |
| Somnium Surge | Metal | Bizkaia | |
| Sönambula | Doom/Death Metal | Bizkaia | |
| Song Of Anhubis | Rock/Metal | Bizkaia | |
| Sons of Decay | Thrash/Black Metal | Gipuzkoa | |
| Sorgerth | Death Metal | Bizkaia | |
| Sorhots | Rock/Metal | Lapurdi | |
| Soulitude | Heavy/Power Metal | Bizkaia | |
| Soziedad Alkoholika | Crossover | Araba | |
| Spirikom | Death Metal | Nafarroa | |
| Stolen Soul | Groove Metal | Bizkaia | |
| Strappado | Brutal Death Metal | Bizkaia | |
| Su Ta Gar | Heavy Metal | Gipuzkoa | |
| Subjugated | Brutal Death Metal | Bizkaia | |
| Surt Ur | Black Metal | Bizkaia | |
| Sweet Rage | AltRock/Metal | Bizkaia | |
| Sykario | Rap Metal | Nafarroa | |
| T-TreintayCuatro | Heavy Metal | Araba | |
| Taken | Power Metal | Nafarroa | |
| The Blackening | Thrash/Groove Metal | Nafarroa |
