| Ogre TaskmasterPortal Second Age · 112 | Portal Second Age | 112 | Uncommon | €0.81 |
| Oji, the Exquisite BladeCommander Legends: Battle for Baldur's Gate · 290 | Commander Legends: Battle for Baldur's Gate | 290 | Uncommon | €0.13 |
| Oji, the Exquisite BladeCommander Legends: Battle for Baldur's Gate · 436 | Commander Legends: Battle for Baldur's Gate | 436 | Uncommon | €0.15 |
| Oji, the Exquisite BladeCommander Legends: Battle for Baldur's Gate · 547 | Commander Legends: Battle for Baldur's Gate | 547 | Uncommon | €0.15 |
| Oji, the Exquisite BladeAlchemy Horizons: Baldur's Gate · 246 | Alchemy Horizons: Baldur's Gate | 246 | Uncommon | — |
| Ojutai MonumentDragons of Tarkir · 242 | Dragons of Tarkir | 242 | Uncommon | €0.05 |
| Oketra's AttendantAmonkhet · 22 | Amonkhet | 22 | Uncommon | €0.03 |
| Oketra's AttendantAmonkhet Remastered · 28 | Amonkhet Remastered | 28 | Uncommon | — |
| Oketra's MonumentAmonkhet · 233 | Amonkhet | 233 | Uncommon | €2.94 |
| Oketra's MonumentDominaria United Commander · 188 | Dominaria United Commander | 188 | Uncommon | €2.50 |
| Oketra's MonumentThe List Tokens · AKH-233 | The List Tokens | AKH-233 | Uncommon | €3.25 |
| Oketra's MonumentAmonkhet Remastered · 277 | Amonkhet Remastered | 277 | Uncommon | — |
| Okiba SalvageKamigawa: Neon Dynasty · 118 | Kamigawa: Neon Dynasty | 118 | Uncommon | €0.04 |
| Okoye, Dora Milaje LeaderMarvel Super Heroes · 27 | Marvel Super Heroes | 27 | Uncommon | €0.09 |
| Old-Fashioned VampireUnstable · 62 | Unstable | 62 | Uncommon | $0.16 |
| Old Fat SpiderThe Hobbit · 132 | The Hobbit | 132 | Uncommon | €0.08 |
| Old Fat Spider Can't See MeThe Hobbit · 50 | The Hobbit | 50 | Uncommon | €0.05 |
| Old FlitterfangWilds of Eldraine · 316 | Wilds of Eldraine | 316 | Uncommon | $0.38 |
| Old-Growth EducatorSecrets of Strixhaven · 207 | Secrets of Strixhaven | 207 | Uncommon | €0.07 |
| Old Hob, Alleycat BluesTeenage Mutant Ninja Turtles · 99 | Teenage Mutant Ninja Turtles | 99 | Uncommon | €0.04 |
| Old Man WillowThe Lord of the Rings: Tales of Middle-earth · 217 | The Lord of the Rings: Tales of Middle-earth | 217 | Uncommon | €0.10 |
| Old Man WillowThe Lord of the Rings: Tales of Middle-earth · 668 | The Lord of the Rings: Tales of Middle-earth | 668 | Uncommon | €0.22 |
| Olivia's BloodswornThe List Tokens · SOI-127 | The List Tokens | SOI-127 | Uncommon | $0.10 |
| Olivia's BloodswornShadows over Innistrad · 127 | Shadows over Innistrad | 127 | Uncommon | €0.13 |
| Olivia's BloodswornShadows over Innistrad Remastered · 127 | Shadows over Innistrad Remastered | 127 | Uncommon | — |
| Ollenbock EscortInnistrad: Double Feature · 294 | Innistrad: Double Feature | 294 | Uncommon | €0.14 |
| Ollenbock EscortInnistrad: Crimson Vow · 27 | Innistrad: Crimson Vow | 27 | Uncommon | €0.09 |
| Omega, Heartless EvolutionFinal Fantasy · 236 | Final Fantasy | 236 | Uncommon | €0.08 |
| Omega, Heartless EvolutionFinal Fantasy · 347 | Final Fantasy | 347 | Uncommon | €0.16 |
| Omega, Heartless EvolutionFinal Fantasy · 501 | Final Fantasy | 501 | Uncommon | $0.66 |
| Omen HawkerMarch of the Machine · 70 | March of the Machine | 70 | Uncommon | €0.20 |
| Omenport VigilanteOutlaws of Thunder Junction · 21 | Outlaws of Thunder Junction | 21 | Uncommon | €0.05 |
| Ominous CemeteryDoctor Who · 189 | Doctor Who | 189 | Uncommon | €0.19 |
| Ominous CemeteryDoctor Who · 794 | Doctor Who | 794 | Uncommon | €3.68 |
| Ominous RoostInnistrad: Double Feature · 65 | Innistrad: Double Feature | 65 | Uncommon | €0.17 |
| Ominous RoostInnistrad: Midnight Hunt · 65 | Innistrad: Midnight Hunt | 65 | Uncommon | €0.18 |
| Ominous SeasIkoria: Lair of Behemoths · 61 | Ikoria: Lair of Behemoths | 61 | Uncommon | €1.42 |
| Ominous SeasThe List Tokens · IKO-61 | The List Tokens | IKO-61 | Uncommon | €1.87 |
| Ominous SphinxHour of Devastation · 41 | Hour of Devastation | 41 | Uncommon | €0.11 |
| Ominous SphinxAmonkhet Remastered · 72 | Amonkhet Remastered | 72 | Uncommon | — |
| Omni-ChangelingLorwyn Eclipsed · 62 | Lorwyn Eclipsed | 62 | Uncommon | €0.24 |
| Omni-ChangelingThe List Tokens · ECL-62 | The List Tokens | ECL-62 | Uncommon | — |
| O-NaginataDouble Masters · 278 | Double Masters | 278 | Uncommon | €0.25 |
| O-NaginataSaviors of Kamigawa · 157 | Saviors of Kamigawa | 157 | Uncommon | €0.51 |
| O-NaginataThe List Tokens · SOK-157 | The List Tokens | SOK-157 | Uncommon | €0.25 |
| Once and FutureThrone of Eldraine · 168 | Throne of Eldraine | 168 | Uncommon | €0.09 |
| Ondu Knotmaster // Throw a LineModern Horizons 3 · 196 | Modern Horizons 3 | 196 | Uncommon | €0.02 |
| Ondu RisingBattle for Zendikar · 41 | Battle for Zendikar | 41 | Uncommon | €0.04 |
| One Dozen EyesCommander 2013 · 159 | Commander 2013 | 159 | Uncommon | €0.11 |
| One Dozen EyesMirrodin · 126 | Mirrodin | 126 | Uncommon | €0.04 |