| Orenda Fink |
24 |
| Orestea |
16 |
| Organ |
7 |
| Organic Infest |
8 |
| Organism 12 |
3 |
| Organismen |
39 |
| Organismen & DJ Large |
5 |
| Organized Konfusion |
36 |
| Orgi 69 |
2 |
| Orgi-E |
8 |
| Orgone |
3 |
| Orgy |
36 |
| Orhan Atasoy |
2 |
| Orhan Gencebay |
141 |
| Orhan Gencebay & Sibel Can |
5 |
| Orhan Hakalmaz |
29 |
| Orhan Veli Kanık |
3 |
| Orhan Ölmez |
29 |
| Oriana Raeo |
3 |
| Orianthi |
40 |
| Orient Expressions |
4 |
| Orient Fall |
9 |
| Oriente |
25 |
| Orietta Berti |
23 |
| Origa |
10 |
| Origami |
5 |
| Origin |
51 |
| Original 3 |
4 |
| Original Alpenland Quintett |
4 |
| Original Broadway Cast |
6 |
| Original Cast |
12 |
| Original Flavor |
3 |
| Original Naabtal Duo |
10 |
| Original Rap Staff |
3 |
| Original Sin |
3 |
| Original Swimming Party |
2 |
| Original Television Soundtrack |
2 |
| Original U.S.A. Gospel Choir |
2 |
| Orillia Opry |
3 |
| Orion Riders |
8 |
| Orion Rigel Dommisse |
15 |
| Orion Too |
3 |
| Orion Too feat. Caitlin |
4 |
| Orion the Hunter |
2 |
| Orion's Reign |
2 |
| Orishas |
68 |
| Orka |
4 |
| Orkest Zonder Naam |
17 |
| Orkiestra Dni Naszych |
3 |
| Orkrist |
14 |
| Orla Fallon |
4 |
| Orla Gartland |
18 |
| Orlando |
14 |
| Orlando Contreras |
15 |
| Orlando Philharmonic Orchestra |
3 |
| Orlando Pops Orchestra |
3 |
| Orlando Silva |
34 |
| Orlane |
13 |
| Orlann Divo |
3 |
| Orleans |
16 |
| Orleya |
16 |
| Orlík |
22 |
| Ormonde |
3 |
| Ornaments of Sin |
3 |
| Ornatos Violeta |
32 |
| Orne |
11 |
| Ornella Vanoni |
116 |
| Ornella Vanoni, Vinícius de Moraes & Toquinho |
2 |
| Ornette |
6 |
| Ornette Coleman |
3 |
| Ornob |
9 |
| Oro Sólido |
7 |
| Orodruin |
7 |
| Orouni |
2 |
| Orphan City |
6 |
| Orphan Hate |
9 |
| Orphan Project |
3 |
| Orphanage |
44 |
| Orphaned Land |
68 |
| Orpheus |
6 |
| Orpheus Omega |
5 |
| Orpheus and Eurydice |
4 |
| Orplid |
14 |
| Orquesta Aragón |
6 |
| Orquesta Dicupé |
3 |
| Orquesta Francini-Pontier |
2 |
| Orquesta Inmensidad |
8 |
| Orquesta La Palabra |
7 |
| Orquesta La Solución |
6 |
| Orquesta Mondragón |
34 |
| Orquesta Narváez |
4 |
| Orquesta Salserín |
16 |
| Orquesta Tabaco Y Ron |
2 |
| Orquesta Típica Fernández Fierro |
3 |
| Orquesta Típica Victor |
2 |
| Orquesta Zodiac |
2 |
| Orquesta de la Luz |
4 |
| Orquesta del Desierto |
8 |
| Orquestra Contemporânea de Olinda |
6 |
| Orquestra Imperial |
12 |