- O
- OO
- OO
- OO
- OO
- OOak
- OakObe
- ObeOBL
- OblObs
- Obsoce
- OceOce
- oceOct
- OctOda
- OdbOdd
- OddOde
- OdeODU
- ODUOf
- OfOff
- OFFOfi
- Ofiogo
- OGROh
- OhOhi
- OhiOIL
- OilOk
- OkOke
- OkeOl
- OlOla
- OlaOld
- OldOl
- OlOlg
- OlgOli
- OliOli
- OliOls
- OlsOMA
- OmaOma
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- OmeOmn
- OmnOn
- OnOne
- ONEOne
- OneOne
- OneOne
- OneONJ
- OnkOnn
- ONOOny
- OnyOos
- OosOpe
- OpOpi
- OpiOpu
- OpuOra
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- OrbOrc
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- OreOrh
- OrhOri
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- OrkOrn
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- OutOv
- OvOve
- OveOve
- OveOwe
- OweOwl
- OwlOxl
- Oxl
- OzaOzo
- OzoOzz
- Opiuo (Australian electronica / breakbeat artist)
- Opiuo feat. Gift of Gab & Syreneiscreamy
- opius dei oficial
- OPLIAM (alternative rock / bed room pop artist)
- OPM (1999–current US dub pop hip‐hop punk reggae group)
- OPM & Big B
- OPM feat. Dirtball, The & Big B
- Opodebota
- Opolopo & Johnson, Angela
- Oportot, Sofía
- Opossom (New Zealand)
- Opozitia
- OPP
- Oppenheimer
- Oppenheimer Analysis
- Oppenheimer MKII
- Oppenheimer, Andy (member of Oppenheimer Analysis)
- Oppera
- Oppermann, Rüdiger
- Oppidan (electro-acoustic producer German Germanov)
- Oppidan (UK garage producer)
- Oppidan & camoufly
- Oppidan & Frisco
- Oppidan & Glader, Hans
- Oppidan & Pocket
- Oppidan & venbee
- Öppna Korten
- Opposing Force (Bay Area Hardcore Band)
- Opposing the Shadows
- 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. 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
- Oproprio, Yago, Rô Rosa & Skeeter Beats
- Opsa Dehëli
- Opshop
- Opskamatrists, The
- Opsomer, Barbara (Belgian singer)
- Opstad, Jon
- Opstand Gospel Choir
- 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)
- Optics (Dutch techno producer)
- Optiganally Yours
- Óptimo (bachata group/artist)
- Optimus Rhyme (US nerdcore hip hop group)
- Option Command
- Options (project of Chicago multi-instrumentalist Seth Engel)
- Optiv & BTK
- Optiv & BTK feat. Ryme Tyme
- Optmus Prime (Mexican nu metal band)
- Opto (Alva Noto + Opiate)
- Optometry (John Tejada & March Adstrum)
- Opulent Construct
- Opuntia (solo project of Mexico City producer Camila de Laborde)
- Opus (Austrian band; track: “Live Is Life”)
- Opus (Latvian pop-rock group)
- Opus & S.T.S.
- Opus Alfa
- Opus Avantra
- Opus Cuatro
- Opus Däi
- Opus Doria
- 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 Kink (UK post-punk group)
- Opus of a Machine
