- O
- OO
- OO
- OO
- OOak
- OakOat
- OatObi
- ObiObs
- ObsOce
- OceOce
- OceOct
- OctOdd
- ODDOde
- OdeODO
- odoOes
- OesOff
- OffOff
- OffOgr
- OGROh
- OhOHN
- OHNOjb
- OjeOKA
- OKAokt
- OktOLA
- OlaOld
- OldOle
- OleOli
- OliOli
- OliOlm
- OlmOlv
- OlvOma
- OmaOme
- OmeOmo
- OmoOna
- ONBOne
- OneOne
- Oneone
- oneONG
- OngOnl
- OnlOnu
- OnuoOo
- Ope
- OpeOpi
- OpiOpu
- OpvOra
- OraOrb
- OrbOrc
- OrcOrd
- OrdOrg
- OrgOri
- OriOri
- Oriorm
- OrnOrp
- OrqOrr
- OrrOrt
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- OsbOsc
- OscOsm
- OsmOst
- OstOTH
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- OttOur
- OurOut
- OutOut
- OutOut
- OutOve
- Oveove
- OveOVX
- OvyOwl
- OwlOxl
- OxlOzc
- OzcOzu
- Ozuozz
- Opium Moon
- Opium Owl (heavy psych rock band from Riga, Latvia)
- OPIUM project (Russian electronic group)
- Opium Warlords
- Opiuo (Australian electronica / breakbeat artist)
- Opiuo feat. Gift of Gab & Syreneiscreamy
- opius dei oficial
- OPLIAM
- OPM (1999–current US dub pop hip‐hop punk reggae group)
- OPM & Big B
- Opodebota
- Opolopo & Johnson, Angela
- Opossom (New Zealand)
- OPP
- Oppenheimer
- Oppenheimer Analysis
- Oppenheimer, Andy (member of Oppenheimer Analysis)
- Oppera
- Oppermann, Rüdiger
- Oppidan
- Oppidan (UK garage producer)
- Oppidan & camoufly
- Oppidan & Frisco
- Oppidan & Pocket
- Oppidan & venbee
- Öppna Korten
- Opposing Force (Bay Area Hardcore Band)
- 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
- Opraah
- OPROER (Belgian indie rock band)
- Oproprio, Yago
- Oproprio, Yago & Patricio Sid
- Opsa Dehëli
- Opshop
- Opskamatrists, The
- Opsomer, Barbara (Belgian singer)
- Opstad, Jon
- Opti-Pop
- Optic
- optic core (experimental electronic/dance producer)
- Optic Nerve, The (80s NY garage rock band)
- Optic Sink
- Optical (UK drum & bass producer Matt Quinn)
- Optical 2
- Optiganally Yours
- Óptimo (bachata group/artist)
- Optimus (US rapper, aka Jordy Towers)
- Optimus Rhyme (US nerdcore hip hop group)
- Optiv & BTK
- Optiv & BTK feat. Ryme Tyme
- Optometry (John Tejada & March Adstrum)
- 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 Alfa
- Opus Atlantica
- Opus Avantra
- Opus Cuatro
- Opus Däi
- Opus featuring Buchebner, Erich, Schiffkowitz and Timischl, Günter
- Opus featuring Falco
- Opus featuring Gruber, Peter Niklas
- Opus featuring Kolonovits, Christian
- Opus featuring Musenbichler, Robby
- Opus III (English techno and house music)
- Opus III (Swedish trio)
- Opus Kink
- Opus Orange
- Opus Pro
- Opus X (Finnish classical ensemble)
- Opus X (Scandinavian pop)
- Opus.
