- 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
- Omnipotence (Canada / Death/Black Metal)
- Omnis (ambient / drone)
- Omniscient (Indian technical death metal band)
- Omnisoul
- Omnispawn
- Omnitica
- Omnitron (Thrash Metal band from Sweden)
- Omnium (Death Metal)
- Omnium Gatherum
- Omnivide
- Omnivortex
- OMNOM (Tech House artist)
- Omnyama, Mfaz'
- Omodaka
- Omodaka (Soichi Terada)
- OMOH (Pop electro french duo)
- Omoi (Sakurai & Kimura)
- Omoinotake
- Omonoko (Northern Irish Alt pop quartet)
- Omoregie, Allen (Nigerian Gospel singer)
- OMORI (Composers of the video game soundtrack “Omori”)
- Omori, Aki
- Omori, Cullen
- Omori, Hinako
- Ōmori, Toshiyuki
- Omosumo
- Omoto, Trevor & UNDY
- Omotola
- OMP
- Omp El Capitán (Dominican Christian music singer)
- OMR (Paris-based French Rapper)
- Omraz (Bulgarian Extreme Metal Band)
- Omri (emo electro)
- Oms, Kuba (Canadian soul singer and producer)
- Omul cu Șobolani
- Omulu & Letrux
- Omulu & Maria Maud
- Omulu + King Doudou
- Omulu, DUDA BEAT & Lux & Tróia
- Omulu, Luna, Luedji & ÀTTØØXXÁ
- OMY, The
- OMYRA & Rubin, Josh
- ON (Sylvain Chauveau and Steven Hess with rotating guest artists)
- ON (solo project of Ken Andrews)
- ON (Hardcore)
- on a créé un monstre
- On a Dead Machine
- On a Friday (pre‐Radiohead group, until 1991)
- On a Hiding to Nothing
- ON AN ON
- On Atlas’ Shoulders
- On Being an Angel
- On Being Human
- On Broken Wings
- On Camera
- On Dead Waves
- On Holiday (Oklahoma City ska punk)
- On Inc.
- On Man
- On Man feat. Falola, Femi
- On My Honor
- On My Life
- On Planets
- On Planets & Blue Wednesday
- On Planets & Flaws
- On Planets & Hanz
- On Point Crew
- On Prend L'Air
- On Regret
- On Solid Ground
- ON THE HUNT & Chandler
- On the Last Day
- On the Line All-Stars, The
- On the Loose (doom metal band from Portugal)
- On the Might of Princes
- On the Rocks (all male a cappella group from the University of Oregon)
- On Thorns I Lay (death/doom/gothic metal band from Greece)
- On Thorns I Lay (French Doom Metal Band)
- On Tonight
- On Trial
- On Video
- On Wave (indie)
- On-lyne (Warframe fictional boy band)
- ON-OFF (AC/DC cover band from northern Italy)
- On-The-Go
- ON! (aka Tequila & the Sunrise Gang) (German punk-rock band)
- ON/OFF (Japanese Band)
- On/Off (Dutch techno duo)
- Ona
- Ona Mae
