O'Connor
hard rock, heavy metal, metal
O'Funk'illo
funk, funk metal, funk rock, rock
O-Zone
dance, eurodance, europop, pop
O.R.O.
dance, eurodance, pop rock, rock
O.T. Quartet
dance, electro, electronic
O.V. Wright
deep soul, rhythm and blues, soul, southern soul
Oak Pantheon
black metal, folk metal, post-metal
Oakhelm
black metal, folk metal, pagan metal, viking metal
Oath To Vanquish
brutal death metal, death metal, grindcore, technical death metal
Obituary
death metal, metal, thrash metal
OBK
electronic, electropop, synthpop
Oblivion Machine
death metal, electronic, industrial death metal, industrial metal