- Onyria (Heavy Rock-France)
- Oniria (Gothic Metal-Argentina)
- Onirica (Black Metal-Italy)
- Orialix (Hard Rock-France)
- Organ Trail (Death Grind-USA)
- Oriax (Death Metal-USA)
- Orias (Metalcore-USA)
- Omnia (Pagan Folk-Netherlands)
- Oregon Trail (Post Hardcore-Switzerland)
- Organ Trails (Black Metal-Switzerland)