| Order to ChargeAncient Sanctuary · 085 | Ancient Sanctuary | 085 | Short Print | €0.13 |
| Order to SmashAncient Sanctuary · 110 | Ancient Sanctuary | 110 | Common | €0.09 |
| Orea, the Sylvan High ArbiterPrimal Origin · 050 | Primal Origin | 050 | Secret Rare | $1.47 |
| Orgoth the RelentlessBattles of Legend: Relentless Revenge · 001 | Battles of Legend: Relentless Revenge | 001 | Secret Rare | $0.17 |
| Orichalcos ShunorosShonen Jump March 2010 subscription bonus · 035 | Shonen Jump March 2010 subscription bonus | 035 | Ultra Rare | €0.11 |
| Orichalcos Sword of SealingMagnificent Monsters · 022 | Magnificent Monsters | 022 | Ultra Rare | €0.13 |
| Orient DragonGeneration Force · 085 | Generation Force | 085 | Secret Rare | $4.40 |
| Origami GoddessAge of Overlord · 027 | Age of Overlord | 027 | Common | €0.04 |
| Original Bamboo SwordDarkwing Blast · 070 | Darkwing Blast | 070 | Common | €0.04 |
| Original Sinful Spoils - Snake-EyeAge of Overlord · 057 | Age of Overlord | 057 | Ultra Rare | €4.93 |
| Orion the Battle KingUnlisted Printings | Unlisted Printings | — | — | — |
| Orphebull the Harmonious Bullfighter BardPhoton Hypernova · 082 | Photon Hypernova | 082 | Ultra Rare | $0.19 |
| Oscillo HeroTournament Pack: 1st Season · 023 | Tournament Pack: 1st Season | 023 | Common | €0.14 |
| OshaleonStardust Overdrive · 036 | Stardust Overdrive | 036 | Short Print | $0.14 |
| OstinatoSoul Fusion · 098 | Soul Fusion | 098 | Common | €0.02 |
| Otherworld - The "A" ZoneForce of the Breaker · 044 | Force of the Breaker | 044 | Common | €0.04 |
| OtohimeLegacy of Darkness · 069 | Legacy of Darkness | 069 | Super Short Print | €0.10 |
| Otonari ThunderSupreme Darkness · 098 | Supreme Darkness | 098 | Super Rare | €0.04 |
| OtoshidamashiLightning Overdrive · 031 | Lightning Overdrive | 031 | Common | €0.03 |
| Outburst DragonGhosts From the Past: The 2nd Haunting · 041 | Ghosts From the Past: The 2nd Haunting | 041 | Ultra Rare | €0.15 |
| Outer Entity AzathotShadows in Valhalla · 018 | Shadows in Valhalla | 018 | Secret Rare | $0.62 |
| Outer Entity NyarlaShadows in Valhalla · 017 | Shadows in Valhalla | 017 | Secret Rare | €0.08 |
| Out of the BlueExtreme Victory · 061 | Extreme Victory | 061 | Common | $0.07 |
| Outrigger ExtensionThe Infinity Chasers · 012 | The Infinity Chasers | 012 | Super Rare | €0.17 |
| Outstanding Dog MarronDark Crisis · 062 | Dark Crisis | 062 | Short Print | €0.02 |
| Outstanding Dog MaryBurst of Destiny · 035 | Burst of Destiny | 035 | Common | €0.06 |
| Overburst DragonChaos Impact · 092 | Chaos Impact | 092 | Rare | €0.10 |
| Over CapacityOrder of Chaos · 077 | Order of Chaos | 077 | Rare | $0.11 |
| Over DestinyDuelist Pack: Aster Phoenix · 021 | Duelist Pack: Aster Phoenix | 021 | Super Rare | €0.06 |
| Overdone BurialCircuit Break · 063 | Circuit Break | 063 | Secret Rare | $0.30 |
| Overdoom LineRaging Battle · 066 | Raging Battle | 066 | Common | €0.08 |
| OverdrivePharaoh's Servant · 060 | Pharaoh's Servant | 060 | Common | €0.02 |
| Overdrive TeleporterCrossroads of Chaos · 083 | Crossroads of Chaos | 083 | Secret Rare | €19.64 |
| OverexaggerationDuelist Nexus · 065 | Duelist Nexus | 065 | Common | €0.02 |
| Overflow DragonDark Neostorm · 004 | Dark Neostorm | 004 | Common | €0.05 |
| Over FusionPower of the Elements · 054 | Power of the Elements | 054 | Common | $0.04 |
| Overlay BoosterLegacy of the Valiant · 006 | Legacy of the Valiant | 006 | Common | €0.07 |
| Overlay CaptureNumber Hunters · 056 | Number Hunters | 056 | Super Rare | $0.09 |
| Overlay EaterGalactic Overlord · 007 | Galactic Overlord | 007 | Common | €0.04 |
| Overlay NetworkMaze of Memories · 020 | Maze of Memories | 020 | Super Rare | €0.09 |
| Overlay OwlGalactic Overlord · 003 | Galactic Overlord | 003 | Common | €0.05 |
| Overlay RegenReturn of the Duelist · 052 | Return of the Duelist | 052 | Common | €0.09 |
| Overlay SentinelLegacy of the Valiant · 005 | Legacy of the Valiant | 005 | Common | €0.09 |
| Over LimitGladiator's Assault · 063 | Gladiator's Assault | 063 | Common | €0.10 |
| Overload FusionPower of the Duelist · 042 | Power of the Duelist | 042 | Rare | $0.03 |
| Overload Future FusionMaze of Muertos · 055 | Maze of Muertos | 055 | Super Rare | €0.19 |
| Overmind ArchfiendExtreme Victory · 044 | Extreme Victory | 044 | Ultra Rare | $1.53 |
| Overpowering EyeStorm of Ragnarok · 094 | Storm of Ragnarok | 094 | Rare | €0.08 |
| Overtex QoatlusExtreme Force · 036 | Extreme Force | 036 | Super Rare | $0.44 |
| Over TuningBattles of Legend: Glorious Gallery · 034 | Battles of Legend: Glorious Gallery | 034 | Secret Rare | $1.17 |