Opus Däi
alternative rock, progressive rock, rock
Opus III
chillout, dance, electronic, techno
Opus Orange
indie pop, surf rock, folk
Orange Goblin
doom metal, hard rock, stoner metal, stoner rock
Orange Juice
indie pop, new wave, post-punk
Orchid Mantis
ambient, dream pop, emo, lo-fi
Orden Ogan
folk metal, power metal, progressive metal
Ordo Rosarius Equilibrio
dark ambient, martial industrial, neofolk
Orgone
afrobeat, death metal, funk, soul, technical death metal
Orion Rigel Dommisse
indie folk, new weird america, singer-songwriter, folk
Orjan Nilsen
melodic trance, progressive trance, tech trance, trance, uplifting trance
Orkrist
black metal, doom metal, folk metal, melodic black metal, symphonic metal
Orla Gartland
indie pop, singer-songwriter
Orleans
classic rock, pop, rock, soft rock
Orleya
bossa nova, chillout, pop
Ornette Coleman
avant-garde, free jazz, jazz
Orodruin
black metal, doom metal, metal