- Number C39: Utopia Ray
- Number C39: Utopia Ray Victory
- Number Return
- Number Wall
- Nutrient Z
- O - Oversoul
- Obedience
- Obelisk the Tormentor
- Obnoxious Celtic Guardian
- Ocean of Regeneration
- Ocubeam
- Odd-Eyes Dragon
- Odin's Eye
- Odin, Father of the Aesir
- Offerings to the Bound Deity
- Offerings to the Doomed
- Offside Trap
- Ojama Black
- Ojama Delta Hurricane!!
- Ojama Delta Thunder!!
- Ojama Delta Wear
- Ojama Green
- Ojama King
- Ojama Trio