- O
- O Metronômio
- O Sebbo
- O Terço
- O V U
- O!jerome
- O.H.M.
- O.R.k.
- Oak
- Oaken Throne
- Oaksenham
- Oberon
- Objekt/Urian
- Oblivion Beach
- OBLIVION DUST
- Oblivion Sun
- Obnosticon
- Obour
- Obsidian Kingdom
- Obskyr
- Obsolete
- OCandango
- Ocaso Lunar
- Occhi Di Lupo
- Occidental Journey
- Ocean
- Ocean Obelix
- Oceans Away
- Oceans Collide
- Ocrilim
- Ocruz
- Octal
- Octawitch
- October Days
- October Equus
- Octopus
- Odawas
- Odd as Per Even
- Odd Dimension
- Odd Palace
- Oddious
- Odditorium
- ODDITY
- Oddjobmen
- OddKnee
- Odi
- Odin
- Odin Irgel Rock
- Odin's Court
- Odinkrsna
- Odiorne
- Odumodneurtse
- Of 1 Force
- Of Wonders & Sorrows
- Oferlund
- Officina la Perfetta
- Officine Messina
- OG
- OGKID
- Ogmasun
- Oh Mun
- Ohanami
- Ohio Canyon Riders
- OHM
- OHM MAID
- Ohm:
- Ohmdo
- Ohmme
- OHMphrey
- OHMS
- Ohmwork
- OHO
- Ohrchitekt
- Ojo Nativo
- Oka Sun
- Oktopus Provance
- Ola Kvernberg
- Olaf geht's gut
- OLD
- Old Bombs
- Old Ears
- Old Monk
- Old Prospectors
- Old Rock City Orchestra
- Old Time Relijun
- Old Worlds
- OldRich at CUni
- Ole Thomas Kemény
- Olga Abdullina
- Olga Bell
- Olio su Telnet
- Olis
- Oliver Augst
- Oliver Berger
- Oliver Engqvist
- Oliver Kronhardt
- Oliver Schell
- Oliver Wakeman
- Olivier de Brito
- Olli Heino
- OLVIA
- Om
- Omar Rodriguez Lopez & Jeremy Michael Ward
- Omar Rodriguez Lopez and Jeremy Michael Ward
- Omar Rodriguez Lopez Quintet
- Omar Rodriguez-Lopez
- Omar Shehata
- Omega Acolytes
- Omni Selassi
- Omnium
- On
- On Fillmore
- ON THE PLATEAU
- On the Roof
- On Trial
- On!Air!Library!
- Once a Wolf
- Once and Future Band
- Once We Were
- Once We Were…
- Ondas Mentales
- One
- One ethnic bali
- One Eyed Hypnotist
- One Hot Drink
- One More
- One Morning Left
- One Ring Zero
- One Wing Left
- One Zero
- Oneida
- Oneida/Liars
- Oneiric
- Oneiros Way
- Oniria
- Only Prey Pray
- Ono
- ONO
- Ono
- Onofree
- Onségen Ensemble
- Ontofield
- Onydia
- Onyric Joy
- Onyx Eyes
- OOIOO
- Oort Cloud
- Open Ear Collective
- Open Mindframe
- Opening Scenery
- Opera Oscura
- Operacycle
- Operentzia
- Opeth
- Ophelia
- Ophicina de Sonhos
- Opia
- Opra Mediterranea
- Opsvik & Jennings
- Opus 3
- Opus Avantra
- Opus Däi
- Opus Empyreus
- Opusculus
- Oracle Hysterical
- Oracles
- Orang
- Orang Biasa
- Orangepeeler
- Oratrism
- Orazio Tristano
- Orbit Service
- Orbital
- Orbs
- Orch Garden
- Orchestra Carbon
- Orchestra Of Fools
- Orchestra Of Spheres
- Orchidia Trip
- Order of the Dying Orchid
- ORDN
- Ordo Equilibrio
- Ordo Rosarius Equilibrio
- Oren Ambarchi
- Oren Amchi
- Oresund Space Collective
- OrfeUs
- OrgAAn
- ORGANIC NOISES
- ORGÖNE
- Orhvynuss
- Oricalkos
- Orient Express
- Origami
- Origin Lost
- Original Motion Picture Soundtrack
- ORION
- Orion
- ORION
- Ormyst
- Orne
- Orph
- Orpheum Black
- Orphia
- Orquesta Metafisica
- Orquestra dos Corpos Mortos
- Orricle
- Orso
- Orthodox
- Orthrelm
- Orton
- Orvar Ormbunke
- Os Bardos
- Os Chinchilas
- Os Joseense
- Os Mundi
- Os Mutantes
- Osage Tribe
- Osaka La Band
- Osanna
- Oscar Brambila
- Oscillator/Modulator
- Oscura Materia
- Osfera
- OSI
- Osiris
- Osirys
- OSLO
- Osmosis
- Osmüga
- Ossi Duri
- OSSI DURI (& Ike Willis, Elio, Mike Kenneally )
- Osta Love
- Ostracon
- OSTROVSKYBAND
- Osvaldo De La Fuente
- Osvaldo Dufour
- Oteme
- Others
- OTI