- O.a.T.H.
- O.B.C.Collection
- O.d.I.O.
- O.S.T - Dazed & Confused
- O.S.T.-Roller (By Goblin)
- O.T. Factor
- O.Z.
- O'Williams,Wendy
- Oak
- Oaks
- Oath of Damnation
- Oath to Vanquish
- Oathbreaker
- Oathean
- Obelyskkh
- Oberer Totpunkt
- Oberschlesien
- Obey the Brave
- Obituaries
- Obituary
- Object of Aggression
- Obliterate
- Obliteration
- Obliterations
- Obliveon
- Oblivion Beach
- Oblivion Protocol
- Oblivious
- Oblivious Signal
- Obnoxious Youth
- Obscene Eulogy
- Obscene Execration
- Obscenity
- Obscura
- Obscura Amentia
- Obscurant
- Obscure Infinity
- Obscure Sphinx
- Obscured By Clouds
- Obscuring Veil
- Obscurity
- Obscuro
- Obsecration
- Obsequiae
- Obsessed the
- Obsessed, the
- Obsession
- Obsidian Gate
- Obsidian Kingdom
- Obsidious
- Obszön Geschöpf
- Obtained Enslavement
- Obtest
- Obtruncation
- Obús
- Occult
- Ocean
- Ocean Alley
- Ocean Between Us
- Ocean Chief
- Ocean Colour Scene
- Ocean Depths
- Ocean Grave
- Ocean Grove
- Ocean of Grief
- Ocean Thief
- Oceanlord
- Oceano
- Oceans
- Oceans Ate Alaska
- Oceans of Night
- Oceans of Sadness
- Oceans of Slumber
- Oceans Over Earth
- Oceanwake
- Ockra
- Octagon Man,the
- Octave One
- Octavia Sperati
- Octinomos
- October Falls
- October File
- October Thorns
- October Tide
- Octoploid
- Odd Crew
- Odd Project
- Oddland
- Odem Arcarum
- Odious Mortem
- Odium
- Odium Humani Generis
- Odium Immortalis
- Odium Inc.
- Odroerir
- Oerjgrinder
- Oerjgrinder & Calvaria Fuck Fever
- Of Legends
- Of Mice & Man
- Of Mice & Men
- Of Mice and Men
- Of Mice&Men
- Of Virtue
- Ofdrykkja
- Ofermod
- Off Minor
- Offenbach & Vic Vogel Big Band
- Officer Negative
- Officium Triste
- Oficina G3
- OGRE
- Oh
- Oh Hiroshima
- Oh No Joe
- Oh Sleeper
- Oh the Horror
- OHGR
- Ohhms
- Ohrenfeindt
- Oil
- Oil 10
- Oil Seed Rape
- Oiler
- Oklahoma Kid
- Oklahoma Kid,the
- OLD
- Old Canes
- Old Canes (Appleseed Cast)
- Old Corpse Road
- Old Dead Tree
- Old Dirty Buzzard
- Old Fire
- Old Forest
- Old Funeral
- Old Graves
- Old Growth
- Old Man Child
- Old Man Gloom
- Old Man Lizard
- Old Man s Will
- Old Man's Child
- Old Man's Gloom
- Old Mans Child
- Old Mother Hell
- Old Ruins
- Old Season
- Old Silver Key
- Old Tower
- Old Wainds
- Old Wizard
- Old Wolf
- Old Wounds
- Olde
- Olemus
- Olhava
- Oliver Dawson Saxon
- Oliver Magnum
- Oliver-Dawson Saxon
- Olympos Mons
- Olzon, Anette
- Olzon,Anette
- Om
- Omega Crom
- Omega Diatribe
- Omega I
- Omega Infinity
- Omega Lithium
- Omega Massif
- Omega Swarm,the
- Omegavortex
- Omen
- Omen Faculty
- Omen of Ruin
- Omen Omen
- Ominous Grief
- Ominous Resurrection
- Ominous Ruin
- Omission
- Omnia
- Omnia Malis Est
- Omnia Moritur
- Omnioid
- Omnium Gatherum
- On a Dead Machine
- On A Pale Horse
- On a Warpath
- On Broken Wings
- On Paths of Torment
- On the Brink
- On the Floor
- On the Outside
- On Thorns I Lay
- Once Awake
- Once Beloved
- Once Human
- Once More
- Once Nothing
- Once Upon a Winter
- Onchocerciasis Esophagogastroduodenoscopy
- Ondfodt
- Ondfødt
- Ondskapt
- Ondt Blod
- One Bad Pig
- One Bad Son
- One Bullet Left
- One Day as a Lion
- One Desire
- One Dice
- One Fingered Fist
- One Four One
- One Free Fall
- One Hit Wonder
- One Hour Hell
- One Human
- One Hundred & Eight
- One Hundred Demons
- One Hundred Suns
- One Hundred Twenty
- One in Vain
- One Inch Giant
- One King Down
- One Last Legacy
- One Life Crew
- One Machine
- One Man Army and the Undead Quartet
- One Minute Silence
- One More Word
- One Morning Left
- One Point Three
- One Step Beyond
- One Step Closer
- One Tail, One Head
- One Thousand Homo DJ's
- One Two Three Four
- One Way Mirror
- One Way System
- One Win Choice
- One Without
- One-Way Mirror
- Oneida
- Ongoing Concept
- Onkel Tom Angelripper
- Onkos
- Onlap
- Only Living Witness
- Onmyōza
- Onslaught
- Ontal
- Onward to Olympas
- Onyx Cathedral
- Oomph!
- Opearation: Mindcrime
- Open Eyes Elysia
- Open Hand
- Opera Diabolicus
- Opera IX
- Opera Magna
- Operation: Mindcrime
- Operation:Music Storm
- Operus
- Opeth
- Ophidian I
- Ophiolatry
- Ophis
- Ophtalamia
- Ophthalamia
- Opiate for the Masses
- Opium Warlords
- Opposed to Violence
- Opposite Earth
- Opposition of One
- Oppressor
- Opprobrium
- Optimum Wound Profile
- Opus Irae
- Opus Majestic
- Or Not
- Orange Goblin
- Orange Island
- Orange Man Theory
- Orangeburg Massacre
- Orangutang
- Oranssi Pazuzu
- Orbit Culture
- Orchestrated Onslaught
- Orchid
- Orchid's Curse
- Orcustus
- Ordeal & Plight
- Orden Ogan
- Order
- Order from Chaos
- Order of 315
- Order of Chaos
- Order Of Destruction
- Order of Ennead
- Order of Isaz
- Order of Nine
- Order of the Ebon Hand
- Order of the Solar Temple
- Order of the Solar Temple, the
- Order of the Static Temple
- Order of Týr
- Ordinance
- Ordo Caper
- Ordo Equilibrio
- Ordo Funebris
- Ordo Rosarius Equilibrio
- Organic
- Organic Illusion
- Organic Infest
- Orgy
- Orianthi
- Oriflamme
- Origami Galaktika
- Origin
- Origin Blood
- Origin of Zed
- Original Iron Men
- Original London Cast Recording
- Original Off Broadway Cast
- Original Revival London Cast
- Original Studio Cast
- Origine
- Orion the Hunter
- Orkus
- Orm
- Orme Le
- Oro
- Orodruin
- Orphan Hate
- Orphan Skin Diseases
- Orphanage
- Orphanage Named Earth
- Orphaned Land
- Orphaned Land & Amaseffer
- Orplid
- Orth
- Orthodox
- Orthrelm/Behold the Arctopus
- Osbourne Family Album / O.S.T.
- Oscult
- Osculum Infame
- OSI
- Osi & the Jupiter
- Osi and the Jupiter
- Osiah
- Ossuarium
- Ossuary Insane
- Ossuary,the
- Ost-Front
- Ost/North,Alex (Composer)
- Ost+Front
- Ostermayer Fritz
- OstFront
- Ostrogoth
- Osvajači
- Otargos
- Otep
- Other Eyes Wise
- Other Houses
- Other Star People
- Other, the
- Otto Dix
- Otyg
- Ötzi
- Ou
- Ouija & Anasarca
- Our Ashes Remain
- Our Banshee
- Our Blond Covers
- Our Crimes in Thought
- Our Divinity
- Our Flaws Remain
- Our Hollow Our Home
- Our Hollow,Our Home
- Our Last Enemy
- Our Last Night
- Our Mirage
- Our Place of Worship Is Silence
- Our Survival Depends on Us
- Out Came the Wolves
- Out Cold & Vorhees
- Out of Hand
- Out of Hatred
- Out of Order
- Out of This World
- Out of Trust
- Outbreak Hate
- Outer Heaven
- Outlaw
- Outlaw Blood
- Outlaw Country
- Outlaw Order
- Outlaws of Ravenhurst
- Outline in Color
- Outrage
- Outrage A.D.
- Outside
- Outworld
- Ov Hell
- Over My Dead Body
- Over the Voids
- Over the Voids...
- Over Your Threshold
- Overcast
- Overcome
- Overdose
- Overdrive
- Overdrivers
- Overkill
- Overkill L.A.
- Overmars
- Overthrone
- Overthrow
- Overtorture
- Owane
- Owl
- Owl in Daylight
- Owls Woods Graves
- Oxiplegatz
- Öxxö Xööx
- Oxygen Destroyer
- Oz
- Oz Knozz
- Oz Noy
- Ozark Mountain Dared
- Ozark Mountain Daredevils
- Ozric Tentacles
- Ozzfest: Second Stage Live
- Ozzy Osbourne
