| Obscura InterceptorStreets of New Capenna · 389 | Streets of New Capenna | 389 | Rare | €0.59 |
| Obscura PolymorphistAlchemy: New Capenna · 24 | Alchemy: New Capenna | 24 | Rare | — |
| Obscuring AetherDragons of Tarkir · 194 | Dragons of Tarkir | 194 | Rare | $0.18 |
| Obscuring AetherMurders at Karlov Manor Commander · 179 | Murders at Karlov Manor Commander | 179 | Rare | €0.15 |
| Obscuring HazeCommander 2020 · 61 | Commander 2020 | 61 | Rare | €3.42 |
| Obscuring HazeCommander Masters · 308 | Commander Masters | 308 | Rare | $4.77 |
| Obscuring HazeCommander Masters · 566 | Commander Masters | 566 | Rare | €10.49 |
| Obscuring HazeCommander Masters · 701 | Commander Masters | 701 | Rare | €7.03 |
| Obscuring HazeAvatar: The Last Airbender Eternal · 313 | Avatar: The Last Airbender Eternal | 313 | Rare | €12.10 |
| Observed StasisFinal Fantasy Commander · 40 | Final Fantasy Commander | 40 | Rare | $0.28 |
| Observed StasisFinal Fantasy Commander · 113 | Final Fantasy Commander | 113 | Rare | $0.49 |
| Obsessive CollectorAlchemy: Innistrad · 19 | Alchemy: Innistrad | 19 | Rare | — |
| Obsessive PursuitAvatar: The Last Airbender Promos · 112s | Avatar: The Last Airbender Promos | 112s | Rare | €0.62 |
| Obsessive PursuitAvatar: The Last Airbender · 112 | Avatar: The Last Airbender | 112 | Rare | $0.64 |
| Obsessive PursuitAvatar: The Last Airbender · 340 | Avatar: The Last Airbender | 340 | Rare | €1.29 |
| Obsidian CharmawModern Horizons 2 · 137 | Modern Horizons 2 | 137 | Rare | €1.70 |
| Obsidian CharmawModern Horizons 2 · 353 | Modern Horizons 2 | 353 | Rare | $1.93 |
| Obsidian CharmawModern Horizons 2 Promos · 137s | Modern Horizons 2 Promos | 137s | Rare | €5.28 |
| Obsidian ObeliskDominaria United Commander · 18 | Dominaria United Commander | 18 | Rare | €0.10 |
| Obsidian ObeliskDominaria United Commander · 94 | Dominaria United Commander | 94 | Rare | €0.70 |
| Obstinate BalothIconic Masters · 179 | Iconic Masters | 179 | Rare | €0.11 |
| Obstinate BalothMagic 2011 · 188 | Magic 2011 | 188 | Rare | €0.33 |
| Obstinate FamiliarOdyssey · 210 | Odyssey | 210 | Rare | €0.52 |
| Obzedat, Ghost CouncilModern Masters 2017 · 176 | Modern Masters 2017 | 176 | Rare | €0.91 |
| Obzedat's AidDragon's Maze · 89 | Dragon's Maze | 89 | Rare | €0.22 |
| Occult EpiphanyCrimson Vow Commander · 14 | Crimson Vow Commander | 14 | Rare | €0.75 |
| Occult EpiphanyCrimson Vow Commander · 52 | Crimson Vow Commander | 52 | Rare | $1.07 |
| Occult EpiphanyReality Fracture Commander · 43 | Reality Fracture Commander | 43 | Rare | €0.20 |
| Occupation of KulrathUnknown Event · RR02b | Unknown Event | RR02b | Rare | $4.99 |
| Occupation of LlanowarUnknown Event · RG11 | Unknown Event | RG11 | Rare | $100.00 |
| Ocelot PrideStore Championships · 47 | Store Championships | 47 | Rare | €126.99 |
| Ochre JellyAdventures in the Forgotten Realms · 196 | Adventures in the Forgotten Realms | 196 | Rare | €0.42 |
| Ochre JellyAdventures in the Forgotten Realms · 330 | Adventures in the Forgotten Realms | 330 | Rare | $0.38 |
| Ochre JellyAdventures in the Forgotten Realms Promos · 196a | Adventures in the Forgotten Realms Promos | 196a | Rare | €0.90 |
| Ochre JellyAdventures in the Forgotten Realms Promos · 196p | Adventures in the Forgotten Realms Promos | 196p | Rare | €0.38 |
| Ochre JellyAdventures in the Forgotten Realms Promos · 196s | Adventures in the Forgotten Realms Promos | 196s | Rare | €0.94 |
| Octavia, Living ThesisCommander 2021 · 29 | Commander 2021 | 29 | Rare | €0.24 |
| Octavia, Living ThesisCommander 2021 · 356 | Commander 2021 | 356 | Rare | €1.72 |
| Octavia, Living ThesisOutlaws of Thunder Junction Commander · 103 | Outlaws of Thunder Junction Commander | 103 | Rare | €0.61 |
| Octavia, Living ThesisMagic Online Promos · 90026 | Magic Online Promos | 90026 | Rare | — |
| OctomancerBloomburrow Commander · 37 | Bloomburrow Commander | 37 | Rare | $0.39 |
| OctomancerBloomburrow Commander · 69 | Bloomburrow Commander | 69 | Rare | €1.12 |
| Octopus UmbraCommander 2018 · 11 | Commander 2018 | 11 | Rare | €0.39 |
| Octopus UmbraThe List Tokens · C18-11 | The List Tokens | C18-11 | Rare | €1.46 |
| Octopus UmbraTreasure Chest · 70725 | Treasure Chest | 70725 | Rare | — |
| Oddly UnevenThe List (Unfinity Foil Edition) · 6 | The List (Unfinity Foil Edition) | 6 | Rare | $0.23 |
| Oddly UnevenUnstable · 15 | Unstable | 15 | Rare | €0.20 |
| Oddric, Lunar MarquisMystery Booster 2 Tokens · 551 | Mystery Booster 2 Tokens | 551 | Rare | $0.15 |
| Odds // EndsDissension · 153 | Dissension | 153 | Rare | €0.22 |
| Odds // EndsThe List Tokens · DIS-153 | The List Tokens | DIS-153 | Rare | €0.21 |