Signature card

A Signature Card is one (or more) particular card(s) a duelist uses in almost all their Duels and is most associated with them. Signature cards tend to be the most likely to have Alternate artworks. In Yu-Gi-Oh! 5D's, the character's signature card tends to be a Synchro Monster. Most signature monster cards are also called Ace Monsters.

Some video games have a similar concept known as a Key Card, in which the player selects a certain card as their "ace".

Yu-Gi-Oh!

Character	Signature Card(s)
Yami Yugi	Dark Magician Dark Magician Girl Egyptian Gods
Yugi Muto	Silent Swordsman LV0 Silent Magician LV0
Seto Kaiba	Blue-Eyes White Dragon Blue-Eyes Ultimate Dragon XYZ-Dragon Cannon Obelisk the Tormentor
Joey Wheeler	Red-Eyes Black Dragon Flame Swordsman Time Wizard Jinzo Gilford the Lightning
Téa Gardner	Magician of Faith Shining Friendship
Yami Bakura	Dark Necrofear Destiny Board
Mai Valentine	Harpie Lady Harpie's Pet Dragon
Duke Devlin	Orgoth the Relentless
Ryo Bakura	Change of Heart
Solomon Muto	Exodia the Forbidden One Ancient Dragon
Keith Howard	Barrel Dragon Slot Machine Zoa/Metalzoa Zera the Mant
Mako Tsunami	The Legendary Fisherman Fortress Whale
Weevil Underwood	Perfectly Ultimate Great Moth Insect Queen
Rebecca Hawkins	Shadow Ghoul Fire Princess
Rex Raptor	Tyrant Dragon Red-Eyes Black Dragon Serpent Night Dragon
Paradox Brothers	Gate Guardian
Maximillion Pegasus	Toon World Thousand-Eyes Restrict
Hobson	Zombiemaster
Cyber Kaiba	Automatic Giant
Seeker	Exodia the Forbidden One
Espa Roba	Jinzo
Arkana	Dark Magician
Strings	Revival Jam Slifer the Sky Dragon
Lumis and Umbra	The Masked Beast (Umbra) Masked Beast Des Gardius (Lumis)
Marik Ishtar	The Winged Dragon of Ra
Ishizu Ishtar	Exchange of the Spirit
Odion Ishtar	Mystical Beast Serket Temple of the Kings
Noah Kaiba	Shinato, King of a Higher Plane
Gozaburo Kaiba	Exodia Necross
The Big Five(together)	Five-Headed Dragon Berserk Dragon
Gansley	Deepsea Warrior
Crump	Nightmare Penguin
Johnson	Judge Man Hysteric Fairy
Nesbitt	Robotic Knight Perfect Machine King
Lector	Jinzo Satellite Cannon Injection Fairy Lily
Alister	Air Fortress Ziggurat Gorlag
Valon	Armored Gravitation Full Armor Gravitation Double Cloth Armor
Rafael	Guardian Eatos Guardian Dreadscythe
Dartz	The Seal of Orichalcos Divine Serpent
Vivian Wong	Dragon Lady
Shimon Muran	Exodia the Forbidden One
Priest Seto	Blue-Eyes White Dragon
Thief King Bakura	Diabound
Anubis	Pyramid of Light light beast typeSphinx Fallout
Yakou Tenma	The Wicked Avatar The Wicked Eraser The Wicked Dreadroot
Gekkou Tenma	Angel O7
Deschutes Lew	Castle Gate
Tilla Mook	Vampire's Curse
Kirk Dixon	Machina Force
Pete Coppermine	Mutant Mindmaster
Maico Katou/Mrs. Maico	Green Baboon, Defender of the Forest
Mendo Cino	Dreadscythe Harvester
Willa Mette	White-Horned Dragon
Reiko Kitamori	Puppet King
Depre Scott	Zeta Reticulant Greed Quasar
Masumi Momono	Tualatin
Henry Tudor	Dark Magician
Tea (DOR)	Dancing Elf
T. Tristan Grey	Karbonala Warrior
Joey (DOR)	Flame Swordsman
Bakura (DOR)	Dark Plant
Margaret Mai Beaufort	Harpie Lady
J. Shadi Morton	Millennium Golem
Jasper Dice Tudor	Exodia the Forbidden One
Weevil Underwood (DOR)	Basic Insect
Rex Raptor (DOR)	Two-Headed King Rex
Darkness Ruler	King of Yamimakai
Necromancer	Pumpking the King of Ghosts
Keith (DOR)	Slot Machine
Pegasus Crawford (DOR)	Illusionist Faceless Mage
Ishtar (DOR)	Witch of the Black Forest
Richard Slysheen of York	Battle Steer
C. Seto Rosenkreuz	Blue-Eyes White Dragon
Mako (DOR)	Kairyu-Shin
Manawyddan fab Llyr	Skull Knight Chakra

Yu-Gi-Oh! GX

Character	Signature Card(s)
Jaden Yuki	Elemental Hero Flame Wingman (season 1) Elemental Hero Neos (season 2-onward) Yubel Winged Kuriboh Elemental Hero Terra Firma (manga) Polymerization
Alexis Rhodes	Cyber Blader Machine Angel Ritual Ice Queen (manga) Blizzard Princess (manga)
Syrus Truesdale	Power Bond
Chumley Huffington	Des Koala Master of Oz
Chazz Princeton	Ojamas Light and Darkness Dragon (manga)
Brier	Goblin King
Howard X Miller	Monster Register
Belowski	Mokey Mokey King
Chancellor Sheppard	Cyber Ogre 2
Bastion Misawa	Water Dragon Plasma Warrior Eitom Red Ogre (manga)
Zane Truesdale	Cyber End Dragon Cyberdark Dragon Cyber Dragon Cyber Eltanin (manga)
Kagemaru	Sacred Beasts
Prince Ojin	Satellite Cannon
Dr. Eisenstein	Brain Dragon
Camula	Vampire Genesis
Slade Princeton	King Dragun
Dimitri	Dark Magician of Chaos Black Luster Soldier - Envoy of the Beginning
Lyman Banner	Macro Cosmos Helios Trice Megistus
Aster Phoenix	Destiny Hero - Plasma Destiny Hero - Dreadmaster Vision Hero Adoration (manga) Vision Hero Trinity (manga) The Grand Jupiter (manga)
Nightshroud	Darkness Darkness Neosphere
Atticus Rhodes	Red-Eyes Darkness Dragon Ultimate Stage Costume The Atmosphere (manga) The Suppression Pluto (manga)
Jesse Anderson	Rainbow Dragon Princess of Butterflies (manga) The Tripping Mercury (manga)
Axel Brodie	Volcanic Doomfire Electro Sergeant (manga) The Blazing Mars (manga)
Jim Crocodile Cook	Fossil Fusion The Tyrant Neptune (manga)
Adrian Gecko	Cloudian - Eye of the Typhoon Exodius the Ultimate Forbidden Lord Sealed Mantra (manga) The Despair Uranus (manga)
Vellian Crowler	Ancient Gear Golem Ultimate Ancient Gear Golem
Czar	Zoa Metalzoa
Blaze	Thestalos the Firestorm Monarch
Frost	Mobius the Frost Monarch
T-Bone	Granmarg the Rock Monarch
Thunder	Zaborg the Thunder Monarch
The Supreme King	Evil Hero Malicious Edge Evil Hero Dark Gaia Super Polymerization Dark Fusion
Yubel	Yubel Armityle the Chaos Phantom Rainbow Dark Dragon (as Jesse)
Trueman	Dark Archetype
Masked Knight of Anger	Anchor Knight
Masked Knight of Laughter	Fool Clown
Masked Knight of Impassivity	Silent Pain
Yusuke Fujiwara	Honest Clear Vice Dragon (as Nightshroud) Clear World (as Nightshroud)
Sartorius	Arcana Force Ex - the Light Ruler Arcana Force EX - The Dark Ruler
Sarina	Infinite Fiend Summoning Mirrors God of Darkness - Dark God
Professor Viper	Vennominon the King of Poisonous Snakes Vennominaga the Deity of Poisonous Snakes
Seika Kohinata	Evil Dragon Ananta
David Rabb	The Big Saturn
Reggie MacKenzie	Splendid Venus Tethys, Goddess of Light
Principal MacKenzie/Tragoedia	The Supremacy Sun

Yu-Gi-Oh! 5D's

Character	Signature Card(s)
Yusei Fudo	Stardust Dragon Junk Warrior Shooting Star Dragon Lightning Warrior (manga)
Jack Atlas	Red Dragon Archfiend Red Nova Dragon Heavenly King Black Highlander (manga)
Akiza Izinski	Black Rose Dragon Cruel Angel - Queen of Rose (manga)
Luna	Ancient Fairy Dragon Kuribon Regulus
Leo	Power Tool Dragon Life Stream Dragon
Crow Hogan	Black-Winged Dragon Blackwing Armor Master Blackwing Tamer - Hawk Joe the Pitch Dark (manga)
Hunter Pace	Supersonic Skull Flame
Bolt Tanner	Giant Ushi Oni Machina Cannon (manga)
Aero & Blister	Machina Sniper
Trudge	Goyo Guardian
Sector Security	Montage Dragon Gate Blocker
Greiger	Flying Fortress SKY FIRE Earthbound Immortal Chacu Challhua (as a Dark Signer) Ignition Beast Volcannon (manga)
Gill Randsborg	Masked Knight LV7
Commander Koda	Mad Profiler
Professor Frank	Ido the Supreme Magical Force
Sayer	Thought Ruler Archfiend
Kalin Kessler	Hundred-Eyes Dragon (As a Dark Signer) Earthbound Immortal Ccapac Apu (as a Dark Signer) Infernity Doom Dragon Infernity General (Manga)
Carly Carmine	Earthbound Immortal Aslla piscu (as a Dark Signer)
Misty Tredwell	Earthbound Immortal Ccarayhua (as a Dark Signer) Dragon Queen of Tragic Endings
Roman Goodwin	Earthbound Immortal Uru (as a Dark Signer)
Devack	Zeman the Ape King (as a Dark Signer) Earthbound Immortal Cusillu (as a Dark Signer)
Rex Goodwin	Earthbound Immortal Wiraqocha Rasca (as a Dark Signer) Sun Dragon Inti (as a Dark Signer) Moon Dragon Quilla (as a Dark Signer)
Primo	Machine Emperor Wisel Infinity
Ghosts	Ally Salvo
Rudolph Heitmann	Ancient Gear Golem
Dexter	Batteryman AA
Sly	Eccentric Boy
Bob	Flamvell Guard
Patty	Hanewata
Sherry LeBlanc	Chevalier de Fleur Z-ONE Magic Elf Elite Claret (manga)
Bruno	Tech Genus Blade Gunner MAXX-10000
Lester	Machine Emperor Skiel Infinity
Lawton	Gatling Ogre
Elsworth	Determined Daredevil
Bolger	Blood Mephist
Andore	Thunder Unicorn Green Baboon, Defender of the Forest (Fast Power Deck)
Breo	Voltic Bicorn
Jean	Lightning Tricorn
Team Catastrophe	Hidden Knight -Hook- Doom's Ray (Nicolas)
Lazar	Jester Lord Jester Queen Discord
Jakob	Machine Emperor Grannel Infinity
Familiar of Red Nova	Wicked King of Yomi - Mictlan Coatl
Yoshizo Hayashi	Holding-Hands Majin
Taro Yamashita	Sleeping Giant Thud
Jinbei Tanigawa	Holding-Hands Majin
Dragan	Thor, Lord of the Aesir
Brave	Loki, Lord of the Aesir
Harald	Odin, Father of the Aesir
Aporia	Machine Divine Emperor Machinecle Infinity Cubic Machine Divine Emperor Dragon Asterisk
Sect Injuin	Poseidon Giant Beetle Demon King Dragon Beelze
Skeleton Knight	Underworld Dragon Dragonecro
Paradox	Malefic World Malefic Paradox Dragon Malefic Truth Dragon