- Of Legends (Hardcore-USA) - Other name : OL
- Ol Sonuf (Melodic Doom-USA)
- Ol' Scratch (Sludge Doom-USA)
- Ol' Time Moonshine (Stoner Doom-Canada)
- Ol'Dirty (Fusion-France)
- Ola Englund (Progressive Metal-Sweden)
- Olaf (Hard Rock-France)
- Olam Ein Sof (Pagan Folk-Brazil)
- Olamot (Brutal Death-Italy)
- Olan (Heavy Metal-Malaysia)
- Olathia (Thrash Metal-USA)
- OLB (Our Last Breath) (Metalcore-France) - Other name : OLB
- One Last Breath (Post Hardcore-USA) - Other name : OLB
- OurLastBreath (Metalcore-Sweden) - Other name : OLB, Our Last Breath
- One Last Chance (Hardcore-Switzerland) - Other name : OLC
- Olc Sinnsir (Black Metal-France)
- OLD (USA) (Grind Death-USA) - Other name : Old Lady Drivers
- Old (GER) (Thrash Black-Germany)
- Old (CZ) (Thrash Metal-Czechia)
- Old Amoon-Há (Heavy Metal-Brazil)
- Old Betrayer (Black Metal-Colombia)
- Old Black (Black Metal-France)
- Old Black Eternity (Black Metal-Ecuador) - Other name : OBE
- Old Black Majestic (Black Metal-Colombia)
- Old Blood (Black Metal-Spain)
- Old Bones (Black Metal-Sweden)
- Old Burial Temple (Dark Ambient-Australia)
- Old Castles (Dungeon Synth-Chile)
- Old Castles Massacre (Brutal Death-Sri-Lanka)
- Old Cemetery (Doom Metal-Canada)
- Old Chapel (Death Doom-Russia)
- Old Coffin Spirit (Funeral Doom-Brazil)
- Old Corpse Road (Melodic Death Black-United-Kingdom)
- Old Coven (Thrash Black-USA)
- Old Crow (Stoner Doom-USA)
- Old Crow Cry (Folk black-Brazil)
- Old Crucifix (Thrash Black-Mexico)
- Old Cult (Death Black-Brazil)
- Old Curse (Thrash Death-Paraguay)
- Old Demons' Back (Thrash Heavy-France)
- Old Enemies (Stoner-Colombia)
- Old Fashioned (Hardcore-Poland)
- Old Firm (Melodic Death-Slovakia)
- Old Forest (Black Metal-United-Kingdom)
- Old Forgotten Lands (Dark Ambient-USA)
- Old Funeral (Black Death-Norway)
- Old Funereal (Black Metal-Brazil)
- Old Ghoul (Doom Metal-USA)
- Old Goat (Black Metal-USA)
- Old Gods (Hardcore-USA)
- Old Grandad (Stoner Doom-USA)
- Old Graves (Atmospheric Black-Canada)
- Old Growth (Atmospheric Black-Germany)
- Old Habits (Hardcore-USA)
- Old Head (Thrash Heavy-USA)
- Old Hope (Sludge Metal-Canada)
- Old Horn Tooth (Doom Metal-United-Kingdom)
- Old Iron (Sludge Doom-USA)
- Old Iron King (Sludge Metal-United-Kingdom)
- Old James (Hard Rock-Canada)
- Old Kingdom (Black Metal-Mexico)
- Old Legacy (Black Metal-Slovakia)
- Old Legend (ITA) (Black Death-Italy)
- Old Legend (FRA) (Thrash Heavy-France)
- Old Leshy (Black Metal-Poland)
- Old Maid (Thrash Death-United-Kingdom)
- Old Man (Atmospheric Black-El Salvador)
- Old Man Gloom (Sludge Metal-USA) - Other name : OMG
- Old Man Lizard (Stoner-United-Kingdom)
- Old Man Of The Desert (Atmospheric Black-Russia)
- Old Man Savage (Thrash Metal-USA) - Other name : OMS
- Old Man's Child (Symphonic Black-Norway)
- Old Memories (Pagan Black-Norway)
- Old Morgul (Black Metal-Finland)
- Old Mother Hell (Heavy Metal-Germany)
- Old Mysticism (Dungeon Synth-USA)
- Old Nick (Black Metal-USA)
- Old Night (Doom Metal-Croatia)
- Old Noise (Death Thrash-Colombia)
- Old One (Stoner Doom-USA) - Other name : ex- Jack In Irons
- Old Pagan (Black Metal-Germany)
- Old Quantum (Black Metal-France)
- Old Ritual (Black Metal-Italy)
- Old Roger's Revenge (Stoner-Italy)
- Old Ruins (Melodic Black-Germany)
- Old Sacrifice (Thrash Black-Peru)
- Old School (Thrash Metal-Morocco) - Other name : Old Skool
- Old Scythia (Pagan Black-Ukraine)
- Old Season (Symphonic Heavy-Ireland)
- Old Serpent (Heavy Metal-Greece)
- Old Serpents (Death Black-Peru)
- Old Silver Key (Avantgardiste Black-Ukraine)
- Old Skin (Black Death-USA)
- Old Skull (Black Death-Austria)
- Old Sorcery (FIN) (Dungeon Synth-Finland)
- Old Sorcery (Death Doom-Portugal)
- Old Soul (Experimental Metal-USA)
- Old Sparky (Death Thrash-France)
- Old Spectre (Black Metal-Brazil)
- Old Spell (Atmospheric Black-Sweden)
- Old Stove (Stoner-Brazil)
- Old Throne (BRA) (Black Metal-Brazil)
- Old Throne (MEX) (Symphonic Black-Mexico)
- Old Torments (Melodic Doom-Colombia)
- Old Tower (Dungeon Synth-Netherlands)
- Staryi Sklep (Thrash Metal-Russia) - Other name : Old Vault
- Old Village (Dark Ambient-Portugal)
- Old Wainds (Black Metal-Russia)
- Old Whiskey Funeral (Black Death-USA)
- Old Witch (Doom Black-USA)
- Old Witch Cemetery (Doom Metal-Bangladesh)
- Old Wolf (Heavy Metal-USA)
- Old Wounds (Hardcore-USA)
- Old Yron (Heavy Metal-Italy)
- Oldael (Folk Metal-France)
- Oldblood (UK) (Stoner Doom-United-Kingdom)
- Oldblood (FIN) (Death Metal-Finland)
- Oldblood (SVK) (Thrash Black-Slovakia)
- Oldd Wvrms (Sludge Metal-Belgium)
- Olde (Black Metal-Ireland)
- Olde Bard (Black Heavy-USA)
- Olde Crone (Doom Metal-United-Kingdom)
- Olde Growth (Stoner Doom-USA)
- Olde Throne (Melodic Black-New-Zealand)
- Olde York (Hardcore-USA)
- Oldeath (Black Metal-Chile)
- Olden (Folk Death-USA)
- Oldenhelm (Atmospheric Black-USA)
- Oldenwood (Heavy Metal-Bulgaria) - Other name : Soul Hospital
- Older Jack (Heavy Metal-Brazil)
- Oldfiend (Black Metal-USA)
- Oldmoon (Death Doom-Colombia)
- Oldöds (Death Metal-Sweden)
- Oldowan Gash (Black Metal-USA)
- Oldschool (Hard Rock-Russia)
- Oldskull (THA) (Death Metal-Thailand)
- Oldskull (FRA) (Death Metal-France)
- Oldskull (VEN) (Thrash Metal-Venezuela)
- Olduvai (Melodic Heavy-Spain)
- Oldwitch (Doom Metal-Croatia)
- Evenrude (NOR) (Hard Rock-Norway) - Other name : Ole Evenrud - Ole I'Dole
- Oleander (Hard Rock-USA)
- Oleg Izotov (Guitar Hero-Russia) - Other name : ???? ??????
- Oleg Serkov (Experimental Metal-Russia)
- Olemus (Dark Metal-Austria)
- Olethrio Rigma (Metalcore-Greece)
- Olfaction (Grindcore-USA)
- One Last Hero (Electro Metal-Germany) - Other name : OLH
- Olhava (Atmospheric Black-Russia)
- Olho Seco (Hardcore-Brazil)
- Olhon (Dark Ambient-Italy)
- Olhrimnir (Folk Metal-Finland)
- Oligarquia (Death Metal-Brazil)
- Olim (Atmospheric Black-Canada)
- Olio Tähtien Takana (Black Metal-Finland)
- Oliphant Morn (Dungeon Synth-Canada)
- Oliva (Progressive Heavy-USA) - Other name : Jon Oliva
- Olive (Doom Black-Syria)
- Oliver (Post Hardcore-Argentina)
- Oliver Dawson Saxon (Heavy Metal-United-Kingdom) - Other name : ODS, ex-Son Of A Bitch
- Oliver Kaah (Electro Black-Germany)
- Oliver Magnum (Speed Metal-USA)
- Oliver Weers (Heavy Metal-Denmark)
- Olivia Neutered John (Grind Death-United-Kingdom)
- Olkoth (Black Metal-USA)
- Olkoth (USA-2) (Black Death-USA)
- One Last Legacy (Heavy Metal-Germany) - Other name : OLL
- One Last Look (Electro Metal-USA) - Other name : OLL
- Olli Heino (Progressive Metal-Finland)
- Olli Kivelä (Melodic Death-Finland)
- Olm (Black Metal-USA)
- Our Last Night (Post Hardcore-USA) - Other name : OLN
- Olocausto (Porno Gore Grind-Italy)
- Olokoun (Symphonic Metal-Belgium)
- Olorin (Doom Metal-USA)
- Olovan (Black Metal-Czechia)
- Our Lady Peace (Grunge-Canada) - Other name : OLP
- One Less Reason (Alternative Metal-USA) - Other name : OLR
- Olten (Atmospheric Sludge-Switzerland) - Other name : Ølten
- Oltretomba (DK) (Doom Black-Denmark)
- Oltretomba (ITA) (Black Metal-Italy)
- Oltrezona (Metalcore-Italy)
- Olum (Doom Black-Turkey) - Other name : Ölüm
- Oluparún (Death Grind-Ecuador)
- Olv (Experimental Metal-France)
- Olvido (Dark Metal-Spain)
- Olvy (Heavy Metal-Russia)
- Olxane (Atmospheric Black-Netherlands)
- Olymp (Heavy Metal-Germany)
- Olympos Mons (Melodic Power-Finland)
- Olympus (Black Death-France)
- Olympus Mons (ROU) (Gothic Doom-Romania)
- Olympus Mons (FRA) (Atmospheric Metal-France)
- Olÿphant (Heavy Metal-USA) - Other name : Olyphant
- Olzirtox (Black Metal-USA)
