Oak Pantheon
Oberon
Obituary
Ocean Machine
October Tide
Odes of Ecstasy
Odor of Pears
Odyssey
Offering74
Offspring
Ohm
OLD
Old Funeral
Old Man Gloom
Old Man's Child
Olemus
Olive
Omega Supreme
Omnium Gatherum
One Inch Tall
One Step Beyond
Only Crime
Onslaught
On Thorns I Lay
Opeth
Ophthalamia
Oranssi Pazuzu
Oratory
The Orb
Ordained
Origin
Orisha Shakpana
Orphanage
Orphaned Land
Osbourne, Ozzy
Ostomy
The Other Two
Ours
Overkill
Overlord
Oxiplegatz