- O
- oO
- OO
- OO
- OOak
- OakObe
- ObeOBL
- OBLOca
- OcaOce
- OceOct
- OctODA
- OdaOde
- Ode
- ODMOes
- OetOff
- OffOff
- OffOgr
- OgrOh
- OhOi
- OiOjo
- OjoOke
- OkeOl
- OlOld
- OldOld
- OldOli
- OliOli
- OliOll
- OllOly
- OlyOma
- OmaOmi
- OMIOMY
- ONOnd
- OndOne
- OneOne
- OneOne
- OneONL
- ONL
- OnoOok
- OokOpe
- OpeOpi
- OpiOqu
- OquOra
- OraOrb
- OrbOrc
- OrcOre
- OreOri
- OriOri
- OriOrl
- OrlOrp
- OrpOrq
- Orqort
- OrtOsa
- OsaOsc
- OscOsk
- OskOst
- OstOte
- OteOtr
- OtrOtt
- OttOur
- OurOut
- OutOut
- OutOut
- OutOve
- OveOVE
- OVEOwe
- OweOws
- OwuOya
- OyeOzo
- Ozoozz
- 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
- Opitz, Barbi
- Opium (Belgian all girl pop group)
- Opium du Peuple
- Opium Jukebox
- 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
- Opossom (New Zealand)
- OPP
- Oppenheimer
- Oppenheimer Analysis
- Oppenheimer, Andy (member of Oppenheimer Analysis)
- Oppera
- Oppidan
- Oppidan (UK garage producer)
- Oppidan & Frisco
- Oppidan & venbee
- 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
- Opshop
- Opskamatrists, The
- Opsomer, Barbara (Belgian singer)
- Opti-Pop
- Optic
- optic core (experimental electronic/dance producer)
- Optic Nerve, The (80s NY garage rock band)
- Optic Sink
- 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
- 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 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.
- OQuadro
- Oquendo, Manny y Libre
- Oquendo, Manny's Libre
