List of bands (25):

proAge
Proletaryat
Prong
Psycroptic
Queensryche
Rage
Rage Against The Machine
Raging Speedhorn
Rammstein
Raven
Ravencrown
Red Hot Chili Peppers
Red Method
Retromorphosis
Revocation
Rhapsody of Fire
Ripped To Shreds
Rivers Of Nihil
Rob Zombie
Ronnie Romero