OBLIVION GATE (Finland – Gothic Rock)
OB NIXILIS (USA – Black Metal)
OBSCURUS REX (Greece – Heavy Metal)
OBSERVE THE 93RD (USA – Alternative Metal)
OCEAN’S EDGE (Greece – Progressive Metal)
OCEAN OF LOTION (Norway – Synth Pop/Rock)
OCTALUX (USA – Heavy Metal)
OF SPITE (Finland – Death Metal)
OHMWORK (Norway – Heavy Metal)
THE OKLAHOMA KID (Germany – Progressive Metalcore)
OLAOUTO (Greece – Alternative Rock)
OLD DIRTY BUZZARD (USA – Hard Rock)
OLIVE DARES THE DARKNESS (USA – Alternative Rock)
OMNIVORTEX (Finland – Death Metal)
ONCE UPON A WINTER (Greece – Post-Metal)
ONCHOCERCIASIS ESOPHAGOGASTRODUODENOSCOPY (Canada – Brutal Death Metal)
ONE MORNING LEFT (Finland – Metalcore)
OPEN SURGERY (Sweden – Death Metal)
THE OPTIMIST IN ME (Netherlonds – Alternative Rock)
ORANGE CREEK RIDERS (USA – Alternative Rock)
ORCHID’S CURSE (Canada – Metalcore)
ORO (Sweden – Post/Sludge-Metal)
ORPHAN SKIN DISEASES (Italy – Rock)
ORYAD (USA – Symphonic Metal)
OUR DYING WORLD (USA – Thrash Metal)
OUR HOLLOW OUR HOME (England – Metalcore)
OUR MIRAGE (Germany – Post-Hardcore)
OUTRUN THE DAY (England – Doom Metal)
OVDETH (Finland – Death Metal)
OVERSENSE (Germany – Melodic Metal)
OZUL (Norway – Progressive Rock)