| Band | Genre |
|---|---|
| Oasis | Pop Rock |
| Obituary | Black/Death Metal/Hardcore |
| Obscura | Black/Death Metal/Hardcore |
| Onkel Tom Angelripper | Thrash Metal |
| Oomph! | Industrial Rock |
| Opeth | Black/Death Metal/Hardcore |
| Origin | Black/Death Metal/Hardcore |
| Overkill | Thrash Metal |
| Ozzy Osbourne | Heavy metal |
