| BANDNAME | RECORDS | COUNTRY | STYLE | ADDITIONAL INFO |
|---|---|---|---|---|
| Oblation | demo | USA | Death | |
| Obliteration | ? | OK,USA | ? | |
| Oblivion | Sweden | Thrash/Death | ||
| Obsecration | Sweden | Death/Grind/Thrash | Homepage | |
| One Bad Pig | 4? | USA | Punk | Site 1, 2, 3 |
| Oracle | 1 | USA | Power Metal | |
| Ordained Fate | 1+ | ? | Metal | |
| Outrage | 1 | USA? | Death? | |
| Overcome | 2 | USA | Hardcore | TN Homepage, Homepage |