- O
- OO
- OO
- OO
- OOak
- OakOb
- ObeObl
- OblOBZ
- OCOce
- OceOCT
- OctOct
- OctODD
- OddODG
- OdiODY
- OdyOfe
- OfeOff
- OffOgh
- OghOh
- OhOhm
- OhmOiz
- OizOka
- OkaOkt
- OktOla
- OlaOld
- OldOle
- OleOli
- OliOli
- OliOlo
- OloOlz
- OmOMB
- OMBOmi
- OmiOn
- OnOnd
- OndOne
- OneOne
- Oneone
- Oneonl
- OnlONR
- OnrOol
- oomOpe
- OpeOph
- OphOpu
- OpuOra
- OraOrb
- OrbOrc
- OrcOre
- OreOrg
- OrgOri
- OriOrk
- Ork
- OroOrq
- OrqOrt
- OrtOs
- OsOsb
- OsbOsi
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- Osq
- OtaOti
- OtiOtt
- OttOue
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- OusOut
- OutOut
- OutOv
- OvOve
- OveOvi
- OviOwe
- OweOxi
- OxiOza
- OzaOzu
- Ozuozz
- Ophthalamia
- Opi the Hit Machine
- 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 & camoufly
- Oppidan & Frisco
- Oppidan & venbee
- 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, 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)
- Opstad, Jon
- 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
- 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
