Oak, Ash & Thorn (Pagan/Folk-metal)
Oakenshield (Viking/Folk-metal)
Oakhelm (Pagan Folk Black Metal)
Oak Pantheon (Folk/Pagan/Black Metal)
Oak Roots (Folk-metal)
Obereg (Folk/Pagan Metal)
Obscurity (Pagan/Viking Metal)
Ocelon (Celtic Folk-metal)
ODR (Folk-metal)
Odraedir (Pagan/Folk-metal)
Odroerir (Folk-metal)
Ofärd (Folk-metal)
Ogmiös (Folk-metal)
O’Hamsters (Celtic Punk)
Ol’ Jolly Roger (Pirate Metal)
Omiors (Occitan metal)
Omut (Folk-metal)
Onkel Hryum (Trash/Death/Folk-metal)
Open Access (Folk-metal)
OracleVuh (Folk-metal)
Oprich (Folk-metal)
Orphaned Land (Folk-metal)
Oscenrad (Anglo-Saxon Heathen Metal)
Oskord (Folk-metal)
Othalan (Folk-metal)
Otyg (Folk-metal)