- O
- OO
- OO
- OOak
- OakObe
- ObeObs
- ObsOce
- Oceoch
- OchOct
- OctOde
- OdeOdo
- OdoOfa
- OfaOff
- OffO
- OOha
- OhaOiz
- OizOKA
- OKAOl
- OlOld
- OldOle
- OleOli
- OliOli
- OliOls
- OlsOma
- OmaOml
- OmmOn
- OnOne
- OneOne
- OneOne
- OneOnl
- OnlOny
- OnyOpe
- OpeOpi
- OpiOra
- OraOrb
- OrbOrc
- OrcOre
- OreOri
- OriOrk
- OrkOro
- OrpOrr
- OrrOrw
- OrwOsb
- OsbOsk
- OskOst
- OstOth
- OthOtt
- OttOur
- OurOut
- OutOut
- OutOva
- OvaOve
- OveOwe
- OweOxb
- Oxe
- OzeOZZ
- Opium Owl (heavy psych rock band from Riga, Latvia)
- Opium Warlords
- Opiuo (Australian electronica / breakbeat artist)
- 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
- 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 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)
- Or Bleu
- Or du Commun, L’ (Belgian hiphop)
- Or du Commun, L’ feat. Elvis, Roméo
- Or du Commun, L’ feat. Elvis, Roméo, Caballero, Zwangere Guy
- Or du Commun, L’ feat. Lous and the Yakuza
- Or Noir (French TV show)
- Or, Rotem
- Or, The Whale
- OR3O (fandom music producer/vocalist)
- ORA (classical choir)
- ORA (Danish duo)
- Ora Mate
- Ora the Molecule
- Ora, Rita
- Ora, Rita feat. Brown, Chris
