All performers with the letter 'O'
- O-Town
- O.A.R - Of A Revolution
- O.L.D
- Oasis
- Oathean
- Obituary
- Obliveon
- Obsidian Gate
- Obtained Enslavement
- Obtest
- Occult
- Ocean Colour Scene
- Oceans Of Sadness
- October 31
- Odd Project
- Odes Of Ecstasy
- Odeum
- Odious
- Odious Sanction
- Of The Wand And The Moon
- Ofermod
- Officium Triste
- Offspring
- Offspring, The
- Oingo Boingo
- Ol' Dirty Bastard
- Old
- Old 97's
- Old Dead Tree, The
- Old Man Gloom
- Old Man's Child
- Oleander
- Olemus
- Olive
- Oliver Magnum
- Olivia
- Olivia Newton-John
- OMD
- Omen
- Omnium Gatherum
- On Broken Wings
- On Thorns I Lay
- One King Down
- One Minute Silence
- One Voice
- Onesidezero
- Only Living Witness
- Onslaught
- Onward
- Onyx
- Oomph!
- Opera IX
- Opeth
- Ophthalamia
- OPM
- Oppressor
- Oracle
- Orange Goblin
- Oratory
- Order From Chaos
- Ordo Equilibrio
- Organized Konfusion
- Orgy
- Origin
- Originoo Gunn Clapazz
- Orphanage
- Orphaned Land
- Orthanc
- Osculum Infame
- Osdorp Posse
- Osi
- Otyg
- Our Lady Peace
- Ours
- Outfield
- OutKast
- Outlawz
- Overcast
- Overkill
- Overlife
- Oversoul
- Oxide & Neutrino
- Oxiplegatz
- Ozomatli
- Ozzy Osbourne