Optimo
electro, electronic, techno
Optimum Vulnerability
dance, electronic, trance
Optimus Rhyme
hip hop, nerdcore, rap
Opus 5
art rock, jazz, progressive rock
Opus Avantra
avant-garde, progressive rock
Opus Däi
alternative rock, progressive rock, rock
Opus III
chillout, dance, electronic, techno
Opus Orange
indie pop, surf rock, folk
Oral Bee
hip hop, rap, rock
Orang-Utan
classic rock, hard rock, progressive rock, psychedelic rock
Orange 9mm
alternative metal, post-hardcore, rapcore, rock
Orange Avenue
alternative rock, indie rock, rock
Orange Blue
pop, pop rock, rock, soft rock
Orange Goblin
doom metal, hard rock, stoner metal, stoner rock
Orange Grove
reggae, rock, roots reggae
Orange Juice
indie pop, new wave, post-punk
ORANGE RANGE
j-pop, j-rock
Orange Sky
alternative metal, heavy metal, reggae
Orange Sunshine
psychedelic rock, space rock, stoner rock
orange yellow red
dream pop, shoegaze
Orangutang
alternative rock, grunge, punk rock, rock
Oranj Symphonette
avant-garde, jazz, soundtrack
Oratory
metal, power metal, symphonic metal
Orba Squara
chillout, folk
Orca Team
indie pop, lo-fi, post-punk
Orchestra Harlow
funk, latin jazz, salsa
Orchid
doom metal, screamo
Orcus Chylde
doom metal, psychedelic rock, rock, stoner rock
Ordained Fate
christian metal, heavy metal, thrash metal
Orden Ogan
folk metal, power metal, progressive metal
Order Of Ennead
black metal, blackened death metal, death metal, metal
Ordinance
black metal, death metal, progressive death metal, technical death metal
Ordo Equilibrio
dark ambient, martial industrial, neofolk
Ordo Equitum Solis
dark ambient, neofolk
Ordo Funebris
dark ambient, neoclassical, neofolk
Ordo Rosarius Equilibrio
dark ambient, martial industrial, neofolk
Ordog
black metal, doom metal, funeral doom
Oregon Bike Trails
indie pop, indie rock, pop
Orelipoiss
lo-fi, singer-songwriter
Oren Lavie
singer-songwriter, folk