- The Oh Wells
- The Ohio Express
- The Ohio State University Marching Band
- The Old Dead Tree
- The Old Firm Casuals
- The Olivia Tremor Control
- The Olms
- The Once
- The One Up Downstairs
- The Oobi Band
- The Open Mind
- The Open Sea
- The Operation Md
- The Opposites
- The Orange Alabaster Mushroom
- The Orange County Supertones
- The Orange Lights
- The Orchids
- The Organ
- The Original Caste
- The Original Rudeboys
- The Originals
- The Orion Experience
- The Orlons
- The Orphan The Poet
- The Orwells
- The Osborne Brothers
- The Oskadown
- The Osmond Brothers
- The Osmonds
- The Other
- The Other Guys
- The Others
- The Otherside Band
- The Otto Brothers
- The Outline
- The Overtones
- The Overtunes
- The Overtures
- The Oystars
- The Pack
- The Pack Ad
- The Pack After Death
- The Paddingtons
- The Painkillers
- The Pains Of Being Pure At Heart
- The Pale Pacific
- The Panas Dalam
- The Panic Channel
- The Panic Division