| 1801 | | The Orange Peels | |
| 1802 | | The Orange Strips | Indie/Rock |
| 1803 | | The Orb | Ambient/Electronic |
| 1804 | | The Orchid's Curse | |
| 1805 | | The Order Of Elijah | |
| 1806 | | The Ordinaries | |
| 1807 | | The Ordinary Boys | Indie/Rock |
| 1808 | | The Organ | Indie |
| 1809 | | The Organ Beats | |
| 1810 | | The Original Carter Family | |
| 1811 | | The Original Caste | Folk |
| 1812 | | The Original Casuals | |
| 1813 | | The Original Rudeboys | |
| 1814 | | The Original Studio Cast | |
| 1815 | | The Originals | Soul |
| 1816 | | The Orioles | |
| 1817 | | The Orion Experience | Indie/Pop |
| 1818 | | The Orlons | Soul |
| 1819 | | The Orwells | |
| 1820 | | The O's | |
| 1821 | | The Osmonds | 70s/Pop/Rock |
| 1822 | | The Other | Punk |
| 1823 | | The Other Last Project | |
| 1824 | | The Other ) Lyrics by Gypsy Kyss | |
| 1825 | | The Other Ones | 80s/Pop |
70s/80s/Country/Pop
Electronic/Hardcore
Rock
Emo/Hardcore