| 84 | Undead Alchemist | Michael C. Hayes | Blue | R | Innistrad |
| 105 | Undead Alchemist | Michael C. Hayes | Blue | R | Innistrad: Midnight Hunt Commander |
| 118 | Undead Servant | James Zapata | Black | C | Core Set 2020 |
| 124 | Undead Servant | James Zapata | Black | C | Magic Origins |
| 37 | Undead Slayer | Eric Fortune | White | U | Magic 2010 |
| 237 | Undead Sprinter | Nino Vecia | Black/Red | R | Duskmourn: House of Horror |
| 350 | Undead Sprinter | John Thacker | Black/Red | R | Duskmourn: House of Horror |
| 203 | Under the Skin | Fernando Falcone | Green | U | Duskmourn: House of Horror |
| 323 | Under the Skin | Cacho Rubione | Green | U | Duskmourn: House of Horror |
| 47 | Undercellar Sweep | Nino Is | White | U | Commander Legends: Battle for Baldur's Gate |
| 87 | Undercity Necrolisk | Tomasz Jedruszek | Black | U | Guilds of Ravnica |
| 88 | Undercity Scavenger | Tomasz Jedruszek | Black | C | Ravnica Allegiance |
| 126 | Undercity Scrounger | Mike Jordana | Black | C | Kamigawa: Neon Dynasty |
| 270 | Undercity Sewers | Yeong-Hao Han | | R | Murders at Karlov Manor |
| 332 | Undercity Sewers | Sergey Glushakov | | R | Murders at Karlov Manor |
| 110 | Undercity Shade | Dana Knutson | Black | U | Ravnica: City of Guilds |
| 210 | Undercity Uprising | Magali Villeneuve | Black/Green | C | Guilds of Ravnica |
| 89 | Undercity's Embrace | Tyler Walpole | Black | C | Ravnica Allegiance |
| 96 | Undercity's Embrace | Tyler Walpole | Black | C | Ravnica Remastered |
| 620 | Under-Construction Skyscraper (playtest) | Kevin Dubell | | R | Mystery Booster 2: Convention Edition |
| 208 | Underdark Basilisk | Brent Hollowell | Green | C | Adventures in the Forgotten Realms |
| 227 | Underdark Basilisk | Brent Hollowell | Green | C | Alchemy Horizons: Baldur's Gate |
| 334 | Underdark Basilisk | Pedro Potier | Green | C | Adventures in the Forgotten Realms |
| 49 | Underdark Beholder (playtest) | Chris Tulach | Black | C | Mystery Booster |
| Underground Sea | Rob Alexander | | R | Revised Edition |
| Underground Sea | Rob Alexander | | R | Unlimited Edition |
| Underground Sea | Rob Alexander | | R | Limited Edition Beta |
| Underground Sea | Rob Alexander | | R | Limited Edition Alpha |
| 240 | Underground Sea | Rob Alexander | | R | Masters Edition II |
| 256 | Underground Sea | Rob Alexander | | R | Masters Edition IV |
| 323 | Underground Sea | Cliff Childs | | R | Vintage Masters |
| 204 | Undergrowth Scavenger | Nils Hamm | Green | C | Magic 2015 Core Set |
| 359 | Undergrowth Stadium | Yeong-Hao Han | | R | Commander Legends |
| 435 | Undergrowth Stadium | Yeong-Hao Han | | R | Commander Masters |
| 620 | Undergrowth Stadium | Yeong-Hao Han | | R | Commander Masters |
| 666 | Undergrowth Stadium | Ron Spears | | R | Commander Masters |
| 714 | Undergrowth Stadium | Yeong-Hao Han | | R | Commander Legends |
| 104 | Underhanded Designs | Anastasia Ovchinnikova | Black | U | Kaladesh |
| 108 | Underhanded Designs | Anastasia Ovchinnikova | Black | U | Kaladesh Remastered |
| 78 | Undersea Invader | Lorenzo Mastroianni | Blue | C | Kaldheim |
| 366 | Undersea Invader | Lorenzo Mastroianni | Blue | C | Jumpstart 2022 |
| 40 | Undersimplify | Brent Hollowell | Blue | C | Alchemy Horizons: Baldur's Gate |
| 79 | Underwater Tunnel | Titus Lunter | Blue | C | Duskmourn: House of Horror |
| 208 | Underworld Cerberus | Svetlin Velinov | Black/Red | M | Theros |
| 157 | Underworld Coinsmith | Mark Winters | White/Black | U | Journey into Nyx |
| 237 | Underworld Coinsmith | Mark Winters | White/Black | U | Commander 2015 |
| 73 | Underworld Connections | Yeong-Hao Han | Black | R | Duel Decks: Jace vs. Vraska |
| 83 | Underworld Connections | Yeong-Hao Han | Black | R | Return to Ravnica |
| 128 | Underworld Connections | Yeong-Hao Han | Black | R | Commander 2017 |
| 138 | Underworld Connections | Yeong-Hao Han | Black | R | Innistrad: Crimson Vow Commander |
| 138 | Underworld Connections | Yeong-Hao Han | Black | R | Commander 2015 |
| Underworld Dreams | Julie Baroh | Black | U | Legends |
| 115 | Underworld Dreams | Carl Critchlow | Black | R | Magic 2010 |
| 121 | Underworld Dreams | PINDURSKI | Black | U | Theros Beyond Death |
| 167 | Underworld Dreams | Carl Critchlow | Black | R | Ninth Edition |
| 168 | Underworld Dreams | Carl Critchlow | Black | R | Eighth Edition |
| 184 | Underworld Dreams | Carl Critchlow | Black | R | Tenth Edition |
| 162 | Underworld Fires | Bayard Wu | Red | U | Theros Beyond Death |
| 293 | Underworld Sentinel | Vincent Proce | Black | R | Theros Beyond Death |
| Undiscovered Paradise | David O'Connor | | R | Visions |
| Undying Beast | Steve Luke | Black | C | Portal |
| 119 | Undying Flames | Tsutomu Kawade | Red | R | Saviors of Kamigawa |
| Unerring Sling | Zak Plucinski | | U | Mirage |
| 52 | Unesh, Criosphinx Sovereign | Adrian Majkrzak | Blue | M | Hour of Devastation |
| 85 | Unesh, Criosphinx Sovereign | Adrian Majkrzak | Blue | M | Amonkhet Remastered |
| 62 | Unexpected Allies | Milivoj Ćeran | Red | C | Alchemy Horizons: Baldur's Gate |
| 13 | Unexpected Conversion | Kekai Kotaki | Blue | R | Innistrad: Midnight Hunt Alchemy |
| 102 | Unexpected Fangs | Jesper Ejsing | Black | C | Ikoria: Lair of Behemoths |
| 203 | Unexpected Results | Mike Bierek | Blue/Green | R | Gatecrash |
| 25 | Unexpectedly Absent | Min Yum | White | R | Commander 2013 Edition |
| 27 | Unexpectedly Absent | Min Yum | White | R | Commander Anthology |
| 33 | Unexpectedly Absent | Min Yum | White | R | Eternal Masters |
| 106 | Unexpectedly Absent | Min Yum | White | R | Ikoria Commander |
| 17 | Unexplained Absence | Rockey Chen | White | R | Murders at Karlov Manor Commander |
| 328 | Unexplained Absence | Rockey Chen | White | R | Murders at Karlov Manor Commander |
| 56 | Unexplained Disappearance | Izzy | Blue | C | Guilds of Ravnica |
| 70 | Unexplained Vision | Bram Sels | Blue | C | Throne of Eldraine |
| 77 | Unfathomable Truths | Drew Tucker | Blue | C | Modern Horizons 3 |
| 8 | Unfinished Business | Mark Zug | White | R | Wilds of Eldraine Commander |
| 44 | Unfinished Business | Mark Zug | White | R | Wilds of Eldraine Commander |
| Unfulfilled Desires | D. Alexander Gregory | Blue/Black | R | Mirage |
| 45 | Unglued Pea-Brained Dinosaur | Larissa Hasenheit, Mina Jeon, Daria Sergeyeva, Sam Burley | | C | Unfinity |
| 39 | Unhinged Beast Hunt | Larissa Hasenheit, Mina Jeon, Daria Sergeyeva, Sam Burley | | C | Unfinity |
| Unholy Strength | Tom Kyffin | Black | C | Fifth Edition |
| Unholy Strength | Douglas Shuler | Black | C | Fourth Edition |
| Unholy Strength | Douglas Shuler | Black | C | Revised Edition |
| Unholy Strength | Douglas Schuler | Black | C | Unlimited Edition |
| Unholy Strength | Douglas Schuler | Black | C | Limited Edition Beta |
| Unholy Strength | Douglas Schuler | Black | C | Limited Edition Alpha |
| 47 | Unholy Strength | Terese Nielsen | Black | C | Duel Decks Anthology, Divine vs. Demonic |
| 47 | Unholy Strength | Terese Nielsen | Black | C | Duel Decks: Divine vs. Demonic |
| 116 | Unholy Strength | Terese Nielsen | Black | C | Magic 2010 |
| 119 | Unholy Strength | Terese Nielsen | Black | C | Magic 2011 |
| 168 | Unholy Strength | Puddnhead | Black | C | Ninth Edition |
| 168 | Unholy Strength | Gary Ruddell | Black | C | Seventh Edition |
| 169 | Unholy Strength | Puddnhead | Black | C | Eighth Edition |
| 185 | Unholy Strength | Terese Nielsen | Black | C | Tenth Edition |
| 110 | Unicycle (playtest) | Ari Nieh | | C | Mystery Booster |
| 37 | Unidentified Hovership | Jana Heidersdorf | White | R | Duskmourn: House of Horror |
| 305 | Unidentified Hovership | Calder Moore | White | R | Duskmourn: House of Horror |
| 58 | Unified Strike | Dave Dorman | White | C | Onslaught |
| 94 | Unimpeded Trespasser | Dan Scott | Blue | U | Shadows over Innistrad |
| 94 | Uninvited Geist | Dan Scott | Blue | U | Shadows over Innistrad |
| 38 | Unique Charmed Pants | Larissa Hasenheit, Mina Jeon, Daria Sergeyeva, Sam Burley | | C | Unfinity |
| 66 | Unity of Purpose | Jason Felix | Blue | U | Oath of the Gatewatch |
| 235 | Universal Automaton | Ben Maier | | C | Modern Horizons |
| 803 | Universal Automaton | Ben Maier | | C | Jumpstart 2022 |
| 178 | Universal Solvent | Christopher Moeller | | C | Aether Revolt |
| 273 | Universal Solvent | Christopher Moeller | | C | Kaladesh Remastered |
| 342 | Universal Solvent | Joe Slucher | | C | Commander Legends: Battle for Baldur's Gate |
| 347 | Universal Solvent | Christopher Moeller | | C | Commander Legends |
| 804 | Universal Solvent | Christopher Moeller | | C | Jumpstart 2022 |
| 17 | Universal Surveillance | Aaron J. Riley | Blue | R | Kamigawa: Neon Dynasty Commander |
| 54 | Universal Surveillance | Aaron J. Riley | Blue | R | Kamigawa: Neon Dynasty Commander |
| 181 | Unknown Shores | Jung Park | | C | Oath of the Gatewatch |
| 229 | Unknown Shores | Seb McKinnon | | C | Theros |
| 249 | Unknown Shores | Adam Paquette | | C | Theros Beyond Death |
| 259 | Unknown Shores | Rob Alexander | | C | Ixalan |
| 170 | Unleash Fury | Izzy | Red | U | Core Set 2021 |
| 155 | Unleash Shell | Campbell White | Red | C | The Brothers' War |
| 229 | Unleash the Inferno | Zoltan Boros | Black/Red/Green | R | Streets of New Capenna |
| 337 | Unleash the Inferno | Justin & Alexis Hernandez | Black/Red/Green | R | Streets of New Capenna |
| 402 | Unleash the Inferno | Justin & Alexis Hernandez | Black/Red/Green | R | Streets of New Capenna |
| 187 | Unlicensed Disintegration | Izzy | Black/Red | U | Kaladesh |
| 211 | Unlicensed Disintegration | Izzy | Black/Red | U | Kaladesh Remastered |
| 224 | Unlicensed Disintegration | Izzy | Black/Red | U | Double Masters |
| 64 | Unlicensed Hearse | Sean Murray | | R | Outlaws of Thunder Junction Breaking News |
| 246 | Unlicensed Hearse | Chris Seaman | | R | Streets of New Capenna |
| 440 | Unlicensed Hearse | Chris Seaman | | R | Streets of New Capenna |
| 56 | Unliving Psychopath | Greg Staples | Black | R | Dissension |
| 128 | Unlucky Witness | Tyler Walpole | Red | U | Streets of New Capenna |
| 120 | Unmake the Graves | Aaron Miller | Black | C | Magic 2015 Core Set |
| 15 | Unmask | rk post | Black | M | From the Vault: Lore |
| 168 | Unmask | rk post | Black | R | Mercadian Masques |
| 168 | Unnatural Aggression | James Ryman | Green | C | Battle for Zendikar |
| 737 | Unnatural Aggression | James Ryman | Green | C | Jumpstart 2022 |
| 247 | Unnatural Moonrise | Ryan Pancoast | Red/Green | U | Innistrad: Midnight Hunt |
| 191 | Unnatural Restoration | Jeremy Wilson | Green | U | Phyrexia: All Will Be One |
| 32 | Unnatural Selection | Kev Walker | Blue | R | Apocalypse |
| 38 | Unnatural Selection | Kev Walker | Blue | R | Mystery Booster 2: Convention Edition |
| 197 | Unnatural Speed | Wayne Reynolds | Red | C | Champions of Kamigawa |
| 114 | Unnerving Assault | Ron Spencer | Blue/Red | U | Eventide |
| 80 | Unnerving Grasp | Jeremy Wilson | Blue | U | Duskmourn: House of Horror |
| 53 | Unquenchable Thirst | Jeremy Wilson | Blue | C | Hour of Devastation |
| 86 | Unquenchable Thirst | Jeremy Wilson | Blue | C | Amonkhet Remastered |
| 31 | Unquestioned Authority | Alex Horley-Orlandelli | White | U | Judgment |
| 78 | Unquestioned Authority | Zoltan Boros | White | U | Commander 2018 |
| 85 | Unquestioned Authority | Zoltan Boros | White | U | Magic: The Gathering—Conspiracy |
| 260 | Unquestioned Authority | Alex Horley-Orlandelli | White | U | Jumpstart 2022 |
| 389 | Unquestioned Authority | Zoltan Boros | White | U | Commander Legends |
| 50 | Unruly Krasis | Billy Christian | Blue/Green | R | Ravnica Clue Edition |
| 13 | Unsanctioned Ancient Juggler | Larissa Hasenheit, Mina Jeon, Daria Sergeyeva, Sam Burley | | C | Unfinity |
| 109 | Unscrupulous Agent | Michal Ivan | Black | C | Murders at Karlov Manor |
| 112 | Unscrupulous Contractor | Mila Pesic | Black | U | Outlaws of Thunder Junction |
| 114 | Unscythe, Killer of Kings | Karl Kopinski | Blue/Black/Red | R | Alara Reborn |
| 128 | Unseal the Necropolis | Isis | Black | C | March of the Machine |
| Unseen Walker | Alan Rabinowitz | Green | U | Mirage |
| 262 | Unseen Walker | Alan Rabinowitz | Green | U | Classic Sixth Edition |
| 216 | Unsettled Mariner | John Stanko | White/Blue | R | Modern Horizons |
| 38 | Unsettling Twins | Lauren K. Cannon | White | C | Duskmourn: House of Horror |
| 29 | Unshakable Tail | Sean Murray | Black | R | Murders at Karlov Manor Commander |
| 339 | Unshakable Tail | Sean Murray | Black | R | Murders at Karlov Manor Commander |
| 79 | Unspeakable Symbol | Arnie Swekel | Black | U | Scourge |
| 142 | Unstable Amulet | José Parodi | Red | U | Modern Horizons 3 |
| 421 | Unstable Amulet | José Parodi | Red | U | Modern Horizons 3 |
| 153 | Unstable Footing | Nic Klein | Red | U | Zendikar |
| 145 | Unstable Frontier | John Avon | | U | Conflux |
| 41 | Unstable Glyphbridge | Bastien Grivet | White | R | The Lost Caverns of Ixalan |
| 358 | Unstable Glyphbridge | Bastien Grivet | White | R | The Lost Caverns of Ixalan |
| 115 | Unstable Hulk | Ron Spencer | Red | R | Legions |
| Unstable Mutation | Charles Gillespie | Blue | C | Fifth Edition |
| Unstable Mutation | Douglas Shuler | Blue | C | Fourth Edition |
| Unstable Mutation | Douglas Shuler | Blue | C | Revised Edition |
| Unstable Mutation | Douglas Shuler | Blue | C | Arabian Nights |
| 33 | Unstable Mutation | Douglas Shuler | Blue | S | Time Spiral "Timeshifted" |
| 80 | Unstable Mutation | Slawomir Maniak | Blue | U | Ultimate Masters |
| 58 | Unstable Obelisk | William Wu | | U | Commander 2014 |
| 170 | Unstable Obelisk | William Wu | | U | Innistrad: Crimson Vow Commander |
| 220 | Unstable Obelisk | William Wu | | U | Adventures in the Forgotten Realms Commander |
| 227 | Unstable Obelisk | William Wu | | U | Commander 2018 |
| 227 | Unstable Obelisk | William Wu | | U | Commander Anthology 2018 |
| 229 | Unstable Obelisk | William Wu | | U | Commander 2017 |
| 260 | Unstable Obelisk | Johannes Mücke | | C | Warhammer 40,000 Commander |
| 272 | Unstable Obelisk | William Wu | | U | Commander 2021 |
| 416 | Unstable Obelisk | William Wu | | C | Commander Masters |
| 489 | Unstable Obelisk | William Wu | | U | Jumpstart |
| 47 | Unstable Robot Dragon | Larissa Hasenheit, Mina Jeon, Daria Sergeyeva, Sam Burley | | C | Unfinity |
| Unstable Shapeshifter | Terese Nielsen | Blue | R | Tempest |
| 137 | Unstoppable Ash | Brian Snoddy | Green | R | Morningtide |
| 169 | Unstoppable Ogre | Xavier Ribeiro | Red | C | Kamigawa: Neon Dynasty |
| 119 | Unstoppable Slasher | Maxime Minard | Black | R | Duskmourn: House of Horror |
| 294 | Unstoppable Slasher | Maxime Minard | Black | R | Duskmourn: House of Horror |
| 312 | Unstoppable Slasher | SchmandrewART | Black | R | Duskmourn: House of Horror |