- O
- OO
- OO
- OOak
- OakObi
- ObiObs
- ObsOce
- OceOct
- OctOdd
- OddOde
- OdeOef
- OehOff
- OffOgd
- OgdOh
- OhOi
- OiOk
- okOku
- OkuOld
- OldOld
- OldOli
- OliOli
- OliOls
- OlsOMB
- OMBOmn
- OmnO
- OnaOne
- OneOne
- OneOng
- OngOno
- OnoOom
- OomOpe
- OpeOpt
- optOra
- OraOrc
- OrcOrd
- OrdOrh
- OrhOri
- OriOrm
- OrmOrq
- OrqOrt
- OrtOsb
- OsbOsi
- OsiOst
- OstOth
- OthOtt
- OttOur
- OurOut
- OutOut
- OutOve
- OveOve
- OveOwe
- OweOxl
- OxlOzm
- OZMOZZ
- Oomph! feat. Hagen, Nina
- Oomph! feat. Harms, Chris
- Oomph! feat. Jandová, Marta
- Oomph! feat. L'ÂME IMMORTELLE
- Oomph! feat. L’Âme Immortelle
- Oompie Koerier
- Oona (Graphic artist born Oona Leganovic)
- Oona (Oona Garthwaite and Dave Tweedie)
- Oonagh (Senta-Sofia Delliponti)
- Oonagh feat. Björn
- Oonagh feat. Celtic Woman
- Oonagh feat. Fischer, Helene
- Oonagh feat. Safri Duo
- Oonagh feat. Santiano
- OoOo
- oOoOO (witch house/electronic producer)
- öOoOoOoOoOo
- Ooopopoiooo
- oop, anna
- Oopopi Symphony Orchestra
- Oorka
- Oort, Bart van (pianist)
- Oôs Joôs (West-Frisian rock & roll group, performing songs in dialect)
- Öösorr
- Oosterhuis, Trijntje
- Oosterhuis, Trijntje & Metropole Orkest
- Oosterhuis, Trijntje feat. Clayton‐Hamilton Jazz Orchestra, The
- Oosterhuis, Trijntje met Kraayenhof, Carel en Jansen, Janine
- Oosterhuis, Trijntje met McComb, Frank
- Oosterhuis, Trijntje met Richie, Lionel
- Oot n' Oots, The
- Ootsuki, Maki
- Ooyy (Henrik Olsson, Swedish composer and producer)
- Ooze (Swedish ambient producer Sebastian Mullaert)
- Ooze, Ivan
- Oozes, The
- Oozora, Subaru
- OP8 (Giant Sand/Lisa Germano collaboration)
- OP8 feat. Germano, Lisa
- Opaali
- Opac (French psych-folk band from Tours (One-man project : Pierre-Alexis Cottereau, but performing in band))
- Opal (80s US alternative rock band)
- Opal In Sky
- Opał (Polish MC)
- Opania, Marian
- Opanije
- Opatovský, Robo
- Opaz
- Opća opasnost
- OPcrotte
- Opeia, Cazzi
- Opel, Billy
- Opel, Jackie
- Open
- Open Air Stereo
- OPEN ARMS (UK Pop Band)
- Open Circle, The
- Open City (Punk Hardcore)
- Open Door
- Open Fifth
- Open Hand (American indie rock band)
- Open Mike Eagle (US rapper and comedian)
- Open Mike Eagle feat. Alpha MC
- Open Mike Eagle feat. Has-Lo
- Open Mike Eagle feat. Kool A.D.
- Open Mike Eagle feat. Megabusive & McGee, Finiki
- Open Mike Eagle feat. Serengeti
- Open Mike Eagle feat. Still Rift and Video Dave
- Open Mike Eagle feat. Toy Light
- Open Mike Eagle feat. Video Dave and Still Rift
- Open Mike Eagle feat.Brown, Danny
- Open Mind, The (68-73 UK psychedelic rock band)
- Open Minded
- Open Palms
- Open Sails
- Open Sea, The
- Open Season (Australian RAC band)
- Open Sky
- Open Skyz
- Open the Skies
- Open University, The
- Open Up and Bleeds, The
- Open, The
- OpenBSD
- Openside
- Opensight (Metal)
- Opensouls
- Opera (Polish group)
- Opera (Italian hard trance project)
- Opera Australia
