| The Ocean Party |
| The Octavarium Orchestra |
| The Octet |
| THE OCTOPUS |
| The Odd Couple |
| The Oddictions |
| The Odds |
| The Oedipus Complex |
| The Off Days |
| The Official Receivers |
| The Offspring |
| The Ogd Trio |
| The Oh Hellos |
| The Oinker Sisters |
| The Okee Dokee Brothers |
| The Olarn Project |
| The Old Christmas Studio |
| The Old Dead Tree |
| The Old Dogs |
| THE OLD ISE |
| The Old Timey String Band |
| The Oliver Moore Band |
| The Olivia Project |
| The Olivia Tremor Control |
| The Olliephonic Horns |
| The Olympians |
| The Olympics |
| The OM Sound |
| The Omen |
| The OMG Girlz |
| The Ominous Seapods |
| The Omy |
| The On the Line All-Stars |
| The Once |
| The One |
| The One AM Radio |
| The One Hundred |
| The One Keon |
| The One World Ensemble |
| The Oneill Twins |
| The Ones |
| The only children |
| The Only Ocean |
| The Only Ones |
| The Open Minds |
| The Opener |
| The Operation M.D. |
| The Ophelias |
| The Opposites |
| The Options |
| The Opus |
| THE ORAL CIGARETTES |
| The Orange Girl |
| The Orange Lights |
| The Orangu-Tones |
| The Orb |
| The Orchard |
| The Orchestra |
| The Orchids |
| The Ordinaires |
| The Ordinary Boys |
| The Organ |
| The Orgels |
| The Orginal Moonmaids Plus One |
| The Orielles |
| The Original |
| The Original Blind Boys of Mississippi |
| The Original Brothers |
| The Original Carter Family |
| The Original Death Row Eastsidaz |
| The Original Five Blind Boys of Alabama |
| The Original Five Blind Boys of Mississippi |
| The Original Harmony Ridge Creekdippers |
| The Original Howlin Wolf and His Orchestra |
| The Original J.B.s |
| The Original Memphis Five |
| The Original Pied Pipers |
| The Original Salty Dogs |
| The Original Soul Seekers |
| The Original Soul Stirrers |
| The Original Tuxedo Jazz Orchestra |
| The Original Wildcat Jass Band |
| The Original Wolverines |
| The Originals |
| The Orioles |
| The Orlons |
| The Orphan Newsboys |
| The Orwells |
| The Osborne Brothers |
| The Oscar Peterson Trio |
| The Oscar Pettiford Orchestra |
| The Osmond Boys |
| The Osmond Brothers |
| The Osmonds |
| The Oster-Welker Jazz Alliance |
| The Ostprausters |
| The Other |
| The Other End |
| The Other Ones |
| The Other Tribe |
