| 541. Odeal | Vocals | 1 |
| 541. Odessa Jorgensen | Violin | 1 |
| 541. Of Montreal | Featured Artist | 1 |
| 541. Ogueji Kenneth Uchenna | Guitar | 1 |
| 541. Oh Pep! | Featured Artist | 1 |
| 541. Ohmme | Featured Artist | 1 |
| 541. Okkervil River | Featured Artist | 1 |
| 541. Oklou | Guitar, Marimba, Piano, Recorder, Vocals | 1 |
| 541. Olabiyi Julius | Keys | 1 |
| 541. Old Crow Medicine Show | Featured Artist | 1 |
| 541. Ole Kirkeng | Bass | 1 |
| 541. Olena Tsybulska | Drums, Vocals | 1 |
| 541. Olga I. González | Background Vocals, Shaker, Tambourine | 1 |
| 541. Oli Harris | Cello | 1 |
| 541. Oli Jefferson | Drums | 1 |
| 541. Oli Langford | Violin | 1 |
| 541. Olive Hannah | Drums | 1 |
| 541. Oliver "Tuku" Mtukudzi | Featured Artist | 1 |
| 541. Oliver Bates Craven | Electric Guitar, Fiddle, Vocals | 1 |
| 541. Oliver Pinnell | Guitar | 1 |
| 541. Oliver Tuttle | Trombone | 1 |
| 541. Olivia 'Livi Lovez' Williams | Vocals | 1 |
| 541. Olivia Donalson | As Anna Of Cleves, Vocals | 1 |
| 541. Olivia Ivory Jean Walker | Vocals | 1 |
| 541. Olivia Tapia | Vocals | 1 |