- O
- oO
- OO
- OO
- OOak
- OakObi
- ObiObs
- ObsOce
- OceOch
- OchOct
- OctOdd
- OddOde
- OdeOed
- OedOff
- OffOff
- OffOgr
- OgOh
- OhOil
- OilOK
- OKOkk
- OKKOla
- OlaOld
- OldOl
- OlOli
- OliOli
- OliOls
- OlsOma
- OmaOme
- OmeOmn
- OmnOna
- OnaOne
- OneOne
- OneOne
- oneONJ
- ONJOno
- OnoOok
- OokOpe
- OpeOph
- OphOpu
- OQuOra
- OraORB
- OrbOrc
- OrcOrf
- OrfOri
- OriOri
- OriOrm
- OrnOrq
- OrqOrs
- ORTOrw
- OrwOsb
- OsbOsi
- OsiOss
- Ossota
- OtCOto
- OTPOtt
- OttOur
- OurOut
- OutOut
- OutOut
- OutOve
- OveOvi
- OviOwe
- OweOxf
- OxfOza
- OzaOzu
- Ozuozz
- Ó (Formerly Eskimeaux)
- O (Martin Damm, techno)
- O (Olivier Marguerit)
- O (Black metal/Grindcore from Italy)
- Ö (Nicolas Petitfrère, aka Nömak)
- O & The Mo
- o Bardo e o Banjo (Brazilian bluegrass band)
- O Bardo e o Mago (Prog group from Brazil)
- Õ C'EST NOUS
- o Cantador, Santanna
- O Captain! My Captain! (German acoustic punk band)
- Ó Ceannabháin, Eoghan (Irish folk musician)
- O Conqueror
- Ó do Forró
- O Emperor (five-piece rock band from Waterford, Ireland)
- O Future
- O Grilo
- Ó hÉanaí, Seosamh (Irish traditional singer Joe Heaney)
- O Inimigo
- O Karaiva
- Ö la Palöma Boys
- Ô Lake
- O Lethe
- O Level
- O Linea
- Ó Lionáird, Iarla
- O Melhor de MPB
- O Mer
- Ô Paon
- O Paradis
- O Pioneers!!!
- O Positive
- O Safari (synth pop duo from Rennes)
- O Samuli A
- O Satânico Dr. Mao e os Espiões Secretos (Brazilian Punk Band)
- Ó Sé, Seán
- O Simbolo
- Ó Súilleabháin, Diarmuid
- O Terno
- O Verme Vencedor
- o Visitante, Luiz
- O Zorn! (sludge metal band from Long Beach, California)
- O-Hum (Iranian band)
- O-Shen
- O-Zone Percussion Group, The
- O‐Town
- O‐Zone (Moldovan eurodance pop group)
- O, Ashley (fictional pop star from Black Mirror TV series)
- O, Bobby
- O, Coco (Danish singer)
- O, Karen
- O, Karen & Danger Mouse
- O, Karen and Kids, The
- O, Karen with Reznor, Trent and Ross, Atticus
- O, Olivia (American solo performances by Olivia Osby)
- O, Rodney
- O, Rodney & Cooley, Joe
- O, The
- O!Kult
- O. (Tash Keary & Joe Henwood)
- O. Cas
- O. Children
- O., Jenny
- O., Jens
- O.A.KLAY
- O.A.R.
- O.B.F.
- O.B.F. feat. Belén Natalí
- O.B.F. feat. Charlie P
- O.B.F. feat. Williamz, Mr.
- O.C. (East-Coast US rapper Omar Credle)
- O.C. (progressive trance artist Özgür Can)
- O.C. & Organized Konfusion
- O.C. feat. Beman, Nick
- O.C. feat. Chubb Rock & Jeru the Damaja
- O.C. feat. Organized Konfusion
- O.C. Supertones, The
- O.C.A.D (Olivia Cipolla and Arie Dixon)
- O.Children
- O.F.T.B. (Watts hip-hop group)
- O.G. (rapper)
- O.G. (German rapper)
- O.G. Black
- O.G. feat. Nimo
- O.G. Pezo
- O.G. Pezo & Lucio101
- O.G. Pezo, LockeNumma19 & Mista Meta
- O.G.C. (US hardcore rap group Originoo Gunn Clappaz)
- O.L.I.V.I.A. (Argentinian experimental pop music)
- O.M.G.
