- Only Men Aloud [Artist]
- Only Now Existing
- Only Once
- Only One
- Only Ones
- Only Paradise
- Only Seven Left
- Only Son
- Only Ten Left
- Only The Message Mattered
- Only Us
- Only Won
- Only Yesterday
- Only You
- Only You're Dreaming
- Onlybeat
- OnlyChiefa
- onlyforward
- onlyone
- Onm
- Onmutu Mechanicks
- Onmyo-Za
- 陰陽座
- Onna
- Onna-Kodomo
- Onney
- Onni Gideon
- Onni Gideon ('Crazy' Gideonin Gipsy Rockers)
- Onni Kuivalainen
- Onni Laihanen
- Onnie
- Onnik Dinkjian
- O.N.N.O.
- Onno de Bruijn
- Onno Krijn
- Onno Tunç
- Onno Tunç
- Onno Witte
- Onnomon