- O2 Online Angels
- O2 Soul
- O2 the Good Bad Guy
- O2B
- O2DM
- O'2L
- O2T
- O2zen
- o3
- O4c
- O5 & Radecek
- O5 & Radeek
- O5 & Radeček
- o9
- O.A.
- OA
- Oa Gunnarsson
- O.A. Hughes
- Oa Party Duo
- Oacid
- O.A.D.
- OAG
- Oahspe
- Oahu
- Oahu Band
- Òai Star
- Oak
- Oak
- Oak
- O.A.K.
- O.A.K.
- Oak and Bone
- Oak and Gorski
- Oak Apple Day Plus the Deadly Pair
- Oak, Ash & Thorn
- Oak Cliff
- Oak Cliff Assassin
- Oak Cliff Hardhittaz
- Oak Cliff T-Bone
- Oak Cliff T-Bone (Walker)
- Oak is Keeping
- Oak Lonetree
- Oak Oak
- Oak Ridge Quartet
- Oak Street Blues
- Oakalla
- Oakbottom
- Oakcee
- Oakdale Carrière
- Oakdale Carrière
- Oakeater
- Oakenfold
- Oakes