- O
- OO
- OO
- OOak
- OakObe
- ObeObs
- ObsOce
- OceOct
- OctOdd
- OddODE
- ODEOdu
- ODVOff
- OffOG
- OGOh
- OHOhm
- OhmOjo
- OjoOki
- OkiOla
- OlaOld
- OldOle
- OleOli
- OliOlo
- OloOma
- OmaOme
- OmeON
- ONOne
- OneONE
- ONEOne
- OneOnl
- OnlOnu
- OnwOpa
- OpaOph
- OphOR
- OrOrb
- OrbOrc
- OrcOre
- OreOri
- OriOrk
- OrkOrp
- OrpOrs
- Orsory
- OrzOsc
- OscOsl
- OslOst
- OstOti
- OtiOtt
- OttOur
- OurOut
- OutOut
- OutOve
- OveOve
- OveOwe
- OweOxm
- OXOOzo
- OzoOZZ
- Octane & DLR
- Octane & DLR feat. Marion
- Octarium
- Octava Dimesión, La (Colombian salsa group in the 1980s/90s)
- Octavarium
- Octave Cat
- Octave Lissner
- Octave Minds (Chilly Gonzales and Boys Noize collaboration)
- Octave Minds feat. Chance the Rapper & Social Experiment, The
- Octave Noire (formerly known as Oh Morice)
- Octave One (Burden brothers, US techno producers)
- Octave One feat. Saunderson, Ann
- Octaves (US hardcore band from Baltimore, MD)
- Octaves, Les
- Octavia (Bolivian pop)
- Octavia Sperati (Norse gothic metal band)
- Octavia Wakes
- Octavian (South-London based rapper)
- Octavian feat. ABRA
- Octavian feat. ASAP Ferg
- Octavian feat. J Rick & Ware, Jessie
- Octavian feat. London, Theophilus
- Octavian feat. Skepta & Phantom, Michael
- Octavian feat. Smokepurpp
- Octavian Ft. Future
- Octavian ft. Gunna & SAINt JHN
- Octavian ft. Phantom, Michael
- Octavian ft. Skepta
- Octavian Winters
- OCTAVIO
- Octavio Mai (French electronic/alternative duo of Juliette Bazenet and Johan Putet)
- Octavio the Dweeb
- Octavus Lupus (Symphonic metal band from Lieusaint, Île-de-France)
- octi
- Octinomos
- OCTiV
- OCTiV feat. Celldweller
- Octo Octa
- October 31 (US Heavy Metal)
- October Burns Black
- October Country
- October Dogs
- October Drift
- October Ends
- October Fall (piano-fueled pop punk band)
- October Falls (Finnish atmospheric black metal)
- October File
- October Jimmy
- October Light
- October London
- October Noir
- October Project
- October Rage
- October Sky
- October Tide
- Octobre (rock band from Quebec)
- Octobre Rouge (French rap group)
- Ôctôctô
- OctoLab
- Octopus (UK britpop group)
- Octopus (1970s German progressive rock group)
- Octopus (1970s Belgian pop band)
- Octopus (Progressive metal band from Chile)
- Octopus (1970s British psychedelic pop band)
- Octopus (1970s UK psychedelic rock band from Hatfield)
- Octopus Montage
- Octopus Project, The
- Octubre (spanish power-pop)
- OCULA
- OCULA feat. Tailor
- Oculist, The
- Oculos (Death/Thrash Metal band from Turkey)
- Oczojebny, Jakub
- Oczojebny, Jakub feat. Kiti
- OD Kokemus
- OD404
- ODA (Pop Singer)
- Oda (French stoner doom band)
- Oda, Kaori (KAORI for Yuki Kajiura)
- Oda, Kazumasa
- Oda, Tetsurou
- Oda, Yuji
- Odal (German pagan black metal band)
- Odani, Misako
- Odar (Bosnian Black Metal from Sarajevo)
- Odawas
- Odbicia, W Witrynach
- ODC (Modern Rock and Metal project created and led by Celia Do)
- Odd (Norwegian singer/songwriter Odd Nordheim)
- Odd (Filipino post-rock band from Dumaguete)
