| O3 | |
| OATHEAN | |
| OBERON | CAN |
| OBEYER | |
| OBITUARY OBITUARY OBITUARY OBITUARY |
USA |
| OBLIK INSTANCE | |
| OBLITERATION | NOR |
| OBLIVEON OBLIVEON |
CAN |
| OBSCENITY OBSCENITY |
GER |
| OBSCENUS | |
| OBSESIA | ROM |
| OCCULT | NED |
| OCTOBER 31 | |
| ODES OF ECSTACY | GRE/ITA |
| ODIUM | |
| OFFENSE | |
| OFFICIUM TRISTE | NED |
| OFFSPRING, THE | |
| O.L.D. | USA |
| OLD MAN'S CHILD OLD MAN'S CHILD OLD MAN'S CHILD |
NOR |
| OMEN | USA |
| OMNIOUS OMNIOUS |
SWE |
| ON THRONE I LAY | GRE |
| OPERA IX OPERA IX OPERA IX |
ITA |
| OPETH OPETH OPETH |
SWE |
| OPHTHALAMIA | ITA |
| OPPOSITE EARTH | |
| OPPRESSOR OPPRESSOR |
USA |
| ORA PRO NOBIS | |
| ORANGE GOBLIN | UK |
| ORDER FROM CHAOS ORDER FROM CHAOS |
USA |
| ORDER OF NINE ANGELS | |
| ORPHANAGE ORPHANAGE |
NED |
| ORPHANED LAND ORPHANED LAND |
|
| OSIRIS OF CADAVERS | |
| OVERBASS | CAN |
 |
USA |
| OVERLORD | |
| OVERSHADOW | |
| OZONE MONDAY | |
| OZZY OSBOURNE OZZY OSBOURNE OZZY OSBOURNE OZZY OSBOURNE |
UK |