Only Crime
hardcore punk, melodic hardcore, punk rock
Only Living Witness
hard rock, metal, metalcore, stoner rock
Onslaught
heavy metal, metal, speed metal, thrash metal
Onyx
gangsta rap, hip hop, rap
Onyx Eyes
gothic metal, symphonic metal
Ooklah the Moc
dub, reggae, roots reggae
Oomph!
industrial metal, metal, rock
oOoOO
chillwave, darkwave, electronic, witch house
Opal
dream pop, paisley underground
Opća Opasnost
hard rock, heavy metal, rock
Open Chapter
alternative rock, hard rock, rock
Open Hand
alternative rock, emo, rock
Opera Chaotique
alternative rock, cabaret, gothic metal
Opera IX
black metal, gothic metal, metal, symphonic black metal
Operadyse
power metal, symphonic metal
Operatika
gothic metal, metal, power metal, symphonic metal