| Oscorp IndustriesThrough the Omenpaths · 179 | Through the Omenpaths | 179 | Rare | — |
| Osgood, Operation DoubleDoctor Who · 191 | Doctor Who | 191 | Rare | €0.22 |
| Osgood, Operation DoubleDoctor Who · 367 | Doctor Who | 367 | Rare | $0.36 |
| Osgood, Operation DoubleDoctor Who · 796 | Doctor Who | 796 | Rare | €2.66 |
| Osgood, Operation DoubleDoctor Who · 958 | Doctor Who | 958 | Rare | $0.55 |
| Oskar, Rubbish ReclaimerNew Capenna Commander · 77 | New Capenna Commander | 77 | Rare | €0.09 |
| Oskar, Rubbish ReclaimerNew Capenna Commander · 177 | New Capenna Commander | 177 | Rare | €1.21 |
| Oskar, Rubbish ReclaimerNew Capenna Commander Promos · 77p | New Capenna Commander Promos | 77p | Rare | €1.00 |
| OssificationCowboy Bebop · 1 | Cowboy Bebop | 1 | Rare | €1.04 |
| Osteomancer AdeptBloomburrow · 103 | Bloomburrow | 103 | Rare | $0.37 |
| Osteomancer AdeptBloomburrow · 312 | Bloomburrow | 312 | Rare | €0.63 |
| Osteomancer AdeptBloomburrow Promos · 103p | Bloomburrow Promos | 103p | Rare | $0.55 |
| Osteomancer AdeptBloomburrow Promos · 103s | Bloomburrow Promos | 103s | Rare | $0.91 |
| Oswald FiddlebenderAdventures in the Forgotten Realms · 28 | Adventures in the Forgotten Realms | 28 | Rare | €1.86 |
| Oswald FiddlebenderAdventures in the Forgotten Realms · 304 | Adventures in the Forgotten Realms | 304 | Rare | $2.00 |
| Oswald FiddlebenderAdventures in the Forgotten Realms Promos · 28a | Adventures in the Forgotten Realms Promos | 28a | Rare | €28.20 |
| Oswald FiddlebenderAdventures in the Forgotten Realms Promos · 28p | Adventures in the Forgotten Realms Promos | 28p | Rare | €2.16 |
| Oswald FiddlebenderAdventures in the Forgotten Realms Promos · 28s | Adventures in the Forgotten Realms Promos | 28s | Rare | €3.02 |
| Otarian JuggernautOdyssey · 305 | Odyssey | 305 | Rare | €0.17 |
| Otawara, Soaring CityKamigawa: Neon Dynasty · 271 | Kamigawa: Neon Dynasty | 271 | Rare | €25.23 |
| Otawara, Soaring CityKamigawa: Neon Dynasty · 414 | Kamigawa: Neon Dynasty | 414 | Rare | €29.18 |
| Otawara, Soaring CityKamigawa: Neon Dynasty · 503 | Kamigawa: Neon Dynasty | 503 | Rare | €31.75 |
| Otawara, Soaring CityKamigawa: Neon Dynasty Promos · 271p | Kamigawa: Neon Dynasty Promos | 271p | Rare | €24.95 |
| Otawara, Soaring CityKamigawa: Neon Dynasty Promos · 271s | Kamigawa: Neon Dynasty Promos | 271s | Rare | €32.01 |
| Otawara, Soaring CityMagic Online Promos · 98123 | Magic Online Promos | 98123 | Rare | — |
| Otawara, Soaring CityMagic Online Promos · 98125 | Magic Online Promos | 98125 | Rare | — |
| Othelm, Sigardian OutcastUniverses Within · 6 | Universes Within | 6 | Rare | €0.06 |
| Othelm, Sigardian OutcastSecret Lair Drop Tokens · 346 | Secret Lair Drop Tokens | 346 | Rare | $5.80 |
| Otherworld AtlasAvacyn Restored · 219 | Avacyn Restored | 219 | Rare | €1.26 |
| Otherworldly EscortMurders at Karlov Manor Commander · 12 | Murders at Karlov Manor Commander | 12 | Rare | €0.18 |
| Otherworldly EscortMurders at Karlov Manor Commander · 323 | Murders at Karlov Manor Commander | 323 | Rare | €0.16 |
| Otherworldly GazeSecret Lair Drop Tokens · 2069 | Secret Lair Drop Tokens | 2069 | Rare | €4.05 |
| OublietteSecret Lair Drop Tokens · 1794 | Secret Lair Drop Tokens | 1794 | Rare | €4.04 |
| Oura, the ImitatorAlchemy: Lorwyn Eclipsed · 22 | Alchemy: Lorwyn Eclipsed | 22 | Rare | — |
| Outcaster TrailblazerOutlaws of Thunder Junction · 173 | Outlaws of Thunder Junction | 173 | Rare | €1.65 |
| Outcaster TrailblazerOutlaws of Thunder Junction · 343 | Outlaws of Thunder Junction | 343 | Rare | $2.51 |
| Outcaster TrailblazerOutlaws of Thunder Junction Promos · 173p | Outlaws of Thunder Junction Promos | 173p | Rare | $1.38 |
| Outcaster TrailblazerOutlaws of Thunder Junction Promos · 173s | Outlaws of Thunder Junction Promos | 173s | Rare | $1.61 |
| Outfitted JousterAlchemy: Wilds of Eldraine · 22 | Alchemy: Wilds of Eldraine | 22 | Rare | — |
| Outland ColossusMagic Origins · 193 | Magic Origins | 193 | Rare | $0.13 |
| Outland ColossusMagic Origins Promos · 193s | Magic Origins Promos | 193s | Rare | €0.23 |
| Outland ColossusMagic Origins Promos · 193★ | Magic Origins Promos | 193★ | Rare | $0.37 |
| Outlaws' MerrimentBreaking News · 51 | Breaking News | 51 | Rare | €0.19 |
| Out of the TombsWarhammer 40,000 Commander · 46 | Warhammer 40,000 Commander | 46 | Rare | $10.14 |
| Out of the TombsWarhammer 40,000 Commander · 46★ | Warhammer 40,000 Commander | 46★ | Rare | $22.53 |
| Out of TimeModern Horizons 2 · 23 | Modern Horizons 2 | 23 | Rare | €0.29 |
| Out of TimeModern Horizons 2 · 383 | Modern Horizons 2 | 383 | Rare | $0.39 |
| Out of TimeModern Horizons 2 · 442 | Modern Horizons 2 | 442 | Rare | $0.36 |
| Out of TimeModern Horizons 2 Promos · 23p | Modern Horizons 2 Promos | 23p | Rare | €0.43 |
| Out of TimeModern Horizons 2 Promos · 23s | Modern Horizons 2 Promos | 23s | Rare | €0.64 |