- O
- OO
- OO
- OO
- OOak
- OakObe
- ObeObr
- ObrOcc
- OccOce
- OceOct
- OctODD
- OddODE
- ODEOdr
- OdsOfd
- OfeOff
- OFFOgh
- OGIOh
- OhOHN
- OhnOje
- OjeOka
- OKAOku
- OkuOla
- OlaOld
- OldOle
- OleOli
- OliOli
- OliOls
- OlsOma
- OmaOme
- OmeOMO
- OmoOnc
- OncOne
- OneOne
- OneOne
- OneONL
- ONLOno
- OnoOok
- OokOpe
- OpeOpi
- OpiOqu
- Oquora
- ORAOrb
- OrbOrc
- OrcOre
- OreOri
- OriOri
- ORIOrl
- Orlorp
- OrpOrq
- OrrOrt
- OrtOsb
- OsbOsc
- OscOsm
- OsmOST
- OSTOth
- OthOtt
- ottotu
- OTUOur
- OurOut
- OutOut
- OutOuu
- OuvOve
- OveOvi
- OviOwe
- OweOxi
- OxiOzc
- OzcOZw
- OZwozz
- 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 Jukebox
- Opium Moon
- Opium Owl (heavy psych rock band from Riga, Latvia)
- OPIUM project (Russian electronic group)
- Opium Warlock
- Opium Warlords
- Opiuo (Australian electronica / breakbeat artist)
- Opiuo feat. Gift of Gab & Syreneiscreamy
- 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
- Optimo (UK techno duo)
- 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 Avantra
- 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 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)
- OQuadro
- Oquendo, Manny y Libre
