| Octopus | Restless Night |
| Oldfield, Mike | Tubular Bells |
| Oldfield, Mike | Amarok |
| Oldfield, Mike | Ommadawn |
| Oldfield, Mike | The Songs Of Distant Earth |
One Speed  | Droopy Butt Begone ! |
| Opera Prima | Opera Prima |
| Opeth | Damnation |
| Opus Five | Contre-Courant |
| Orange Peel | Orange Peel |
| Orford, Martin | Classical Music & Popular Songs |
| Os Mundi | Latin Mass |
| Osanna | L'Uomo |
| Osanna | Palepoli |
| Osibisa | Osibisa |
| Osibisa | Woyaya |
| Out Of Focus | Out Of Focus |
| Out Of Focus | Four Letter Monday Afternoon |
| Ozric Tentacles | Pungent Effulgent |
| Ozric Tentacles | Erpland |
| Ozric Tentacles | Jurassic Shift |
| Ozric Tentacles | Strangitude |
| Ozric Tentacles | Arborescence |
| Ozric Tentacles | Afterswish |
