- O
- OO
- OO
- OO
- OOak
- OakOb
- ObObl
- OblOC
- OCOce
- OCEOct
- OctOcu
- OcuOdd
- OddOdi
- OdiODZ
- OeOff
- OffOff
- Offogo
- ogoOh
- OhOHN
- OhnOje
- OjeOKA
- OKAOku
- OkuOla
- OlaOld
- OldOle
- OleOli
- OliOli
- OliOls
- Ols
- OmaOme
- OmeOmn
- OmnOna
- OnaOne
- OneONE
- Oneone
- OneONI
- OniOnl
- OnlOny
- OnyOos
- OosOpe
- OpeOpp
- OprORA
- OraOrb
- OrbOrc
- OrcOrd
- OrdOrg
- OrgOri
- OriOri
- OriOrm
- OrmOrq
- OrqOrs
- OrsOru
- Osb
- OsbOse
- OseOsm
- OsmOst
- OstOth
- OthOtt
- OttOty
- OtyOur
- OurOut
- OutOut
- OutOut
- OutOve
- OveOvi
- OviOwe
- OweOxa
- OxbOZ
- Oz
- ozz
- O.G.C. (US hardcore rap group Originoo Gunn Clappaz)
- O.M.G.
- o.n.a.
- O.O.D., OOD, Ood
- O.P.KING
- O.R.k.
- O.R.k. feat. Tankian, Serj
- O.R.O. (Italian pop)
- O.S., Arun (Carnatic Vocalist)
- O.S.T.R. (Polish rapper, musician and producer)
- O.S.T.R. & Hades
- O.S.T.R. & Hades (Duo of two polish rappers)
- O.S.T.R. & Marco Polo (Polish rapper and canadian musician producer)
- O.S.T.R. & Marco Polo
- O.S.T.R. & Sofa
- O.S.T.R. feat. El da Sensei
- O.S.T.R. feat. El da Sensei & Fresh, Dan
- O.S.T.R. feat. Evidence
- O.S.T.R. feat. Gibbs
- O.S.T.R. feat. Green
- O.S.T.R. feat. Hades
- O.S.T.R. feat. J, Brother
- O.S.T.R. feat. Kali
- O.S.T.R. feat. Main Flow & Kaze
- O.S.T.R. feat. Młody O
- O.S.T.R. feat. Murray, Keith & Kochan
- O.S.T.R. feat. Nash, Steve & Sacha Vee
- O.S.T.R. feat. Playground Zer0
- O.S.T.R. feat. Sadat X & Cadillac Dale
- O.S.T.R. feat. Sarius
- O.T. Genasis
- O.T. Genasis feat. Young Dolph
- O.T. Quartet
- O.T.R.
- O.Torvald
- O.W.L.
- O.WHEN (Singer-songwriter)
- O.Z (Mongolian R&B, Pop singer)
- O'Bir, Jon (Trance/Progressive-Trance DJ & producer from Nottingham, UK and based in Manchester, UK)
- O'Bir, Jon feat. Fisher
- O'Blivion, Monty (LA darkwave)
- O'Boy (french rapper)
- O'Boyle, Maeve
- O'Brien Sisters, The
- O'Brien-Docker, Ian
- O'Brien, Charlie (singer and filmmaker)
- O'Brien, Chris (US Singer-songwriter)
- O'Brien, Connor
- O'Brien, Joseph (production music composer)
- O'Brien, Joseph (Christian Artist)
- O'Brien, Michael (US AOR/christian vocalist)
- O'Brien, Michael (US christian singer/songwriter, member of Newsong)
- O'Brien, Mollie (folksinger)
- O'Brien, Paul
- O'Brien, Rich
- O'Brien, Sinead (Irish punk poet)
- O'Brien, Tim & Scott, Darrell
- O'Brien, Tim & Scott, Darrell
- O'Brien, Trisha
- O'Bros (O'Bros from Munich, Germany)
- O'Callaghan, Erin
- O'Callaghan, John & Larkin, Betsie
- O'Callaghan, John feat. Cathy Burton
- O'Callaghan, Patricia
- O'Casan
- O'Clock, Apes
- O'Connell, Krista
- O'Connor, Hazel
- O'Connor, Hazel, Hirst, Clare & Sarah Fisher
- O'Connor, Katie (Songwriter from Galway, Ireland)
- O'Connor, Kim
- O'Connor, Mark's Hot Swing Trio
- O'Connor, Michael
- O'Connor, Nora
- O'Connor, Tony (New Age composer)
- O'Day, Anita & Tjader, Cal
- O'Day, Anita with May, Billy
- O'Day, Anita with May, Billy & His Orchestra
- O'Day, Pat (pop/swing vocalist)
- O'Donis, Colby feat. Akon
- O'Donnell, Daniel & Duff, Mary
- O'Donnell, Kevin's, Quality Six
- O'Dowd, Erin
- O'Flaherty, Jack (Jack Fla)
- O'funk'illo
- O'funk'illo y Romero, Kutxi
- O'Hagan, Patrick (Irish tenor)
- O'Hara, Eureka
- O'Hara, Helen
- O'Hara, Maureen
