- O
- OO
- OO
- OOak
- OakObe
- ObeObs
- ObsOce
- OceOct
- OctOdd
- OddODE
- ODEOdu
- ODVOff
- OffOG
- OGOh
- OHOhm
- OhmOjo
- OjoOki
- OkiOla
- OlaOld
- OldOle
- OleOli
- OliOlo
- OloOma
- OmaOme
- OmeON
- ONOne
- OneONE
- ONEOne
- OneOnl
- OnlOnu
- OnwOpa
- OpaOph
- OphOR
- OrOrb
- OrbOrc
- OrcOre
- OreOri
- OriOrk
- OrkOrp
- OrpOrs
- Orsory
- OrzOsc
- OscOsl
- OslOst
- OstOti
- OtiOtt
- OttOur
- OurOut
- OutOut
- OutOve
- OveOve
- OveOwe
- OweOxm
- OXOOzo
- OzoOZZ
- Ophidian & Peacock, Dr.
- Ophidian & Playah, Tha
- Ophidian I
- Ophis (Germany, Metal)
- Ophthalamia
- Opi the Hit Machine
- Opia (indie electronic group: Cole Citrenbaum, DJ Stanfill and colorthought)
- Opiate for the Masses
- Opick
- Opio (Opion Lindsey - US rapper, from Souls of Mischief)
- Opio del Mono
- Opium (Belgian all girl pop group)
- Opium du Peuple
- Opium Jukebox
- Opium Moon
- Opium Owl (heavy psych rock band from Riga, Latvia)
- Opium Warlords
- Opiuo (Australian electronica / breakbeat artist)
- Opiuo feat. D.Sens
- Opiuo feat. Gift of Gab & Syreneiscreamy
- OPM (1999-current US dub pop hip-hop punk reggae group)
- OPM & Big B
- Opodebota
- Opossom (New Zealand)
- OPP
- Oppenheimer
- Oppenheimer Analysis
- Oppenheimer, Andy (member of Oppenheimer Analysis)
- Oppera
- Oppidan
- Oppidan (UK garage producer)
- Opposite The Other
- Opposites, The
- Opposites, The feat. Adje
- Opposites, The feat. Faberyayo & Sjaak
- Opposites, The feat. Hydroboyz & Adje
- Opposites, The feat. Probz, Mr
- Opposites, The feat. Probz, Mr.
- Opposites, The feat. Sef
- Opposites, The feat. Spasmatic
- Opposites, The met Yellow Claw
- Opposition of One
- Opposition, The (London post‐punk band)
- Oppressed, The (Welsh punk/oi)
- Oppressor (US technical death metal)
- Opprobre
- Opprobrium
- OPROER (Belgian indie rock band)
- Opshop
- Opskamatrists, The
- Opsomer, Barbara (Belgian singer)
- Opti-Pop
- Optic
- optic core (experimental electronic/dance producer)
- Optic Sink
- Optiganally Yours
- Optimo (UK techno duo)
- Óptimo (bachata group/artist)
- Optimus (US rapper, aka Jordy Towers)
- Optimus Rhyme (US nerdcore hip hop group)
- Optiv & BTK
- Opuntia (solo project of Mexico City producer Camila de Laborde)
- Opus (Austrian band; track: “Live Is Life”)
- Opus & Ambros, Wolfgang
- Opus & S.T.S.
- Opus 4 (French gipsy swing quartet)
- Opus 78
- Opus Atlantica
- Opus Cuatro
- Opus Däi
- Opus feat. Jerey, Fritz
- Opus featuring Buchebner, Erich, Schiffkowitz and Timischl, Günter
- Opus featuring Falco
- Opus featuring Gruber, Peter Niklas
- Opus featuring Kolonovits, Christian
- Opus III (English techno and house music)
- Opus III (Swedish trio)
- Opus Kink
- Opus Orange
- Opus Pro
- OQuadro
- Oquendo, Manny y Libre
- Oquendo, Manny's Libre
- Oques Grasses
- Oques Grasses & Doble
- Oques Grasses & Payés, Rita
- Oques Grasses & Santa Salut
- Oques Grasses & Stay Homas
- OQueStrada
- OR (rap duo)
