| Impure | Brutal Death Metal | Bizkaia | |
| In Loving Memory | Doom/Death Metal | Bizkaia | |
| In Thousand Lakes | Melodic Death Metal | Bizkaia | |
| Incursed | Viking/Folk Metal | Bizkaia | |
| Infest | Death/Grindcore | Lapurdi | |
| Ingravitö | Rock/Metal | Nafarroa | |
| Inner Turbulence | Heavy Metal | Bizkaia | |
| Insensathors | Metal/Stoner/Rock | Bizkaia | |
| Insohmnio | Rock/Metal | Bizkaia | |
| Instinct | Thrashcore | Bizkaia | |
| Irkaia | Industrial Metal | Nafarroa | |
| ItsOver NineThousand | Metal | Araba | |
| Izei | Rock/Metal | Gipuzkoa | |
| Jhëit | Black Metal | Bizkaia | |
| Kabbalah | Doom/Heavy/Rock | Nafarroa | |
| Kaixton | Thrash/Death Metal | Bizkaia | |
| Kartzarot | Heavy Metal | Bizkaia | |
| Katar | Metalcore | Araba | |
| Katez | Metal | Nafarroa | |
| Kauce | Heavy Rock | Bizkaia | |
| Keziah | Post Metal | Bizkaia | |
| Kharmia | Heavy Metal | Nafarroa | |
| Khous | Metal | Nafarroa | |
| Killers | Speed Metal | Lapurdi | |
| Killiki | Death Metal | Nafarroa | |
| Knives | Death'n'roll | Bizkaia | |
| Kohatu | Metal | Bizkaia | |
| Koma | Thrash'n'roll | Nafarroa | |
| Konbenio del Metal | Heavy Rock | Gipuzkoa | |
| Krait | Heavy/Power Metal | Gipuzkoa |
