- O
- OO
- OO
- OO
- OOaf
- OAFOaK
- OakOBE
- ObeObn
- OBO
- Oce
- OceOCS
- OCTOct
- OctOdd
- OddODE
- ODEOdo
- OdoOf
- OfOff
- OffOff
- OffOgr
- OgrOh
- ohOHM
- OHNOiz
- OizOka
- OkaOkl
- OklOla
- OlaOld
- OldOld
- OldOle
- OleOli
- OliOli
- OliOls
- OlsOm
- OMOma
- OmaOme
- OmeOMO
- OmoOna
- OnaOne
- ONEONE
- ONEOne
- OneONE
- ONEOnl
- OnlOns
- OnsOol
- OolOpe
- OpeOPF
- OpgOpt
- OptOra
- OraOrb
- OrbOrc
- Orcorc
- orcOre
- OreOrh
- OrhOri
- OriOrk
- OrkOrn
- OrnOrq
- OrqOrs
- OrsOrt
- OrtOsb
- OsbOsc
- OscOsl
- OslOst
- OstOte
- OteOTR
- OTROtt
- OttOud
- OueOur
- OurOut
- OUTOut
- OutOut
- OutOve
- OveOve
- OveOwe
- OweOwl
- OwlOxo
- Oxo
- OzOzu
- ozwozz
- Onsind (acoustic pop punk band)
- Onslaught (UK punk/thrash/speed metal band)
- Onslow (Alternative rock band)
- Onsoku Line
- Ontaneda, Sara
- OnTheEdge
- Ontic
- ONTOGYZONEKI
- ontologics
- Ontuak
- onTune
- Onuabuobi, Victor (Nigerian gospel singer)
- Onuka
- Onuka feat. Ukrainian National Academic Orchestra of Folk Instruments
- Onuki, Ami
- Onuki, Taeko
- Onukwulu, Ndidi
- Önül, Abdurrahman
- Önül, Abdurrahman & Karatüre, Celal
- Onuma, Parsley
- onumi
- Onuora, Oku
- Onur Bostancı (Alternative, Pop)
- Onural, Cengiz
- Onurr
- Onward (US band)
- Onward Brass Band (Barbarin/Cottrell, 1960-)
- Onward to Olympas
- Onward, etc.
- Onyanko Club
- Onyeabor, Charles
- Onyeabor, William
- Onyioha, Oby
- Onyria (Oniria)
- Onysus
- ONYVAA
- Onyx (New York hardcore rap group)
- Onyx (Israeli psytrance DJ Yaniv Goldfarb)
- Onyx (IDM artist, track "Under Pressure")
- Onyx & Dope D.O.D.
- Onyx Collective
- Onyx feat. ASAP Ferg & Price, Sean
- Onyx feat. DMX
- Onyx feat. Dope D.O.D.
- Onyx feat. Genovese
- Onyx feat. Havoc
- Onyx feat. Makem Pay
- Onyx feat. Papoose & Cormega
- Onyx feat. Reks
- Onyx feat. Snak the Ripper
- Onyx feat. X1
- Onyx, PTX & Domestic
- Onza (Spanish prog and fusion band)
- Onza (Spanish rock band.)
- Onze‐Mots
- Onze:20
- ONZY
- OOBE (Italian techno/house producer)
- OOBE (Polish Rock Band)
- Ooberfuse
- Ooberman
- Oobik & the Pucks
- OOcarpet (South Korean band)
- Oodaredevil (Yeat collaborator aka DareDevil)
- ooes
- ooes, Pantera Blue
- oofoe
- Oogie
- Ooh La La
- Oohashi, Takuya
- Oohlas, The
- OOHYO
- ooi (German indie pop band)
- Ooi, Imee
- OOJA, Ms. (hiphop)
- OOJA, Ms. feat. LATINO, EL
- Ookay
- Ookay & Byers, Piper
- Ookay & Cesqeaux
- Ookay & Chime
- Ookay & JSTJR
- Ookay & Linney
- Ookay & Sinjin
- Ookay feat. Byers, Piper
- Ookay feat. Renee, Bella
- Ookay feat. Vance, David
- Ookla the Mok (filk group)
- Ooklah the Moc
- Öökülm
- Oolacile
