| 301 | | Offerprästers Orkester | |
| 302 | | Offertorium | |
| 303 | | Office Of Strategic Influence | Electronic |
| 304 | | Office of Strategic Influence (O.S.I.) | Ambient/Electronic |
| 305 | | Office Space Movie | |
| 306 | | Officer Negative | Hardcore/Punk |
| 307 | | Official Euro 2012 Ireland | |
| 308 | | Official Hot Mess | |
| 309 | | Official Kardinal | |
| 310 | | Official Lil Don | |
| 311 | | Official Secrets Act | |
| 312 | | Officinalchemike | Indie/Rock |
| 313 | | Officium Triste | |
| 314 | | Offlaga Disco Pax | Electronic/Indie |
| 315 | | Offlicence | |
| 316 | | Offset | Punk/Reggae |
| 317 | | Offsides | |
| 318 | | Offspring | Pop punk/Punk/Rock |
| 319 | | Offspring, The | |
| 320 | | Offsrping | |
| 321 | | Oficina G3 | Rock |
| 322 | | Ofishal | |
| 323 | | Ofra Haza | World |
| 324 | | O.F.T.B | |
| 325 | | O.F.T.B. f/ 2Pac, Kurupt, Mich'elle, Yaki Kadafi | |
70s/80s/Country/Pop
Electronic/Hardcore
Rock
Emo/Hardcore