| Ophis |
5 |
| Ophthalamia |
25 |
| Ophélie Winter |
46 |
| Opiate For The Masses |
25 |
| Opium Project |
3 |
| Oppenheimer |
5 |
| Oppenheimer Analysis |
6 |
| Oppi |
6 |
| Opposition |
4 |
| Opposition Of One |
5 |
| Opshop |
48 |
| Optiganally Yours |
8 |
| Optimo |
11 |
| Optimus Rhyme |
5 |
| Option 1 |
6 |
| Opus |
17 |
| Opus Dai |
4 |
| Orakle |
4 |
| Orange 9mm |
43 |
| Orange And Lemons |
6 |
| Orange Blue |
33 |
| Orange Day |
5 |
| Orange Goblin |
48 |
| Orange Juice |
50 |
| Orange Letter |
6 |
| Orange Light |
3 |
| Orange Range |
36 |
| Orange Sky |
7 |
| Oranger |
5 |
| Oratorio |
6 |
| Oratory |
5 |
| Orba Squara |
7 |
| Orbision Roy |
5 |
| Orbit |
14 |
| Orbita Wiru |
7 |
| Orbital |
12 |
| Orchestral Manoeuvres In The Dark |
153 |
| Orchid |
38 |
| Orden Ogan |
4 |
| Ordinary Boys |
5 |
| Ordination Of Aaron |
6 |
| Ordo Draconis |
6 |
| Ordo Equilibrio |
35 |
| Ordo Equitum Solis |
4 |
| Ordo Rosarius Equilibrio |
53 |
| Oren Lavie |
18 |
| Orenda Fink |
12 |
| Organism 12 |
12 |
| Orgy |
59 |
| Orianthi |
30 |
| Orient Pearl |
4 |
| Orietta Berti |
9 |
| Origa |
30 |
| Origami |
13 |
| Origin |
29 |
| Original Broadway Cast |
93 |
| Original Broadway Cast Recording |
5 |
| Original Naabtal Duo |
13 |
| Orikasa Ai |
4 |
| Orion's Reign |
8 |
| Orishas |
51 |
| Orkest |
4 |
| Orla Fallon |
4 |
| Orla Gartland |
5 |
| Orlando |
7 |
| Orlando Brown |
10 |
| Orleans |
37 |
| Ornatos Violeta |
41 |
| Ornella Vanoni |
77 |
| Oro |
3 |
| Orodruin |
3 |
| Orouni |
3 |
| Orphan Lily |
3 |
| Orphanage |
9 |
| Orphaned Land |
45 |
| Orquesta Del Desierto |
8 |
| Orso |
9 |
| Orson |
30 |
| Orthodox Celts |
20 |
| Orup |
22 |
| Os 4 Mensageiros |
5 |
| Os Almirantes |
11 |
| Os Cariocas |
5 |
| Os Mutantes |
78 |
| Os Paralamas Do Sucesso |
54 |
| Osage Tribe |
6 |
| Osaka Popstar |
14 |
| Osaka Popstar & The American Legends Of Punk |
6 |
| Osanna |
13 |
| Osb |
6 |
| Osborne Brothers |
3 |
| Osborne Joan |
10 |
| Oscar Benton |
3 |
| Oscar Brand |
11 |
| Oscar D' Leon |
5 |
| Oscar De La Hoya |
9 |
| Oscar De Leon |
3 |
| Oscar Hammerstein |
36 |
| Oscar Peterson |
32 |
| Oscar Zia |
6 |