A Deck Master is a monster that represents the player in a Deck Master Duel. It appears exclusively in the Virtual World arc of the Yu-Gi-Oh! anime, in which it is used in all Duels that take place in Noah's Virtual World.
At the start of a Duel, each Duelist chooses a card from their Deck (either their Main Deck or Fusion Deck) to be their Deck Master. The player's Deck Master starts the Duel visible, but not on the field. Deck Masters provide a Deck Master ability, with that ability being based on the card chosen as the Deck Master.
A player can choose to Special Summon their Deck Master to their side of the field at any time, but if a player's Deck Master is destroyed, they lose the Duel. If a player's Deck Master leaving the field is used to Summon another monster (such as being used as a Fusion Material, Tributed by a card effect that Summons another monster, or allowing a card such as "A Deal with Dark Ruler" to meet its activation conditions), the replacement monster becomes the player's new Deck Master. If multiple players' Deck Masters are used to Summon a single monster this way, the Summoned monster becomes the Deck Master of all players whose Deck Masters were used for its Summon.
If Fusion Monster was Fusion Summoned by using a Deck Master as Fusion Material, the Summoned Fusion Monster (now a Deck Master itself) can attack that same turn. (Under Battle City Rules, which the Virtual World arc uses a variant of, Fusion Monsters normally cannot attack the turn they are Summoned.)
List of Deck Masters
|Blue-Eyes White Dragon||Virtual Seto Kaiba (demonstration only)||Fusion Monsters you control can attack during your turn, ignoring other rules and effects.[Notes 1]|
|Total Defense Shogun||Total Defense Shogun (demonstration only)||Total Defense Barrier: When a monster your opponent controls declares an attack, you can pay 1000 Life Points to destroy the attacking monster.[Notes 2]|
|Deepsea Warrior||Gansley||Reflector Hole: When a monster you control is attacked, you can Tribute 2 monsters to negate the attack and inflict damage to your opponent equal to the attacking monster's ATK.|
|Kuriboh||Yugi Muto/Yami Yugi||Once per turn, during either player's turn, you can negate damage to you from an opponent's card. Then, Special Summon this card if it is not already on the field.|
|Nightmare Penguin||Crump||Turbo Charger: All face-up WATER monsters you control gain 200 ATK.|
|Dark Magician Girl||Téa Gardner||Soul Circle: During your turn, you can reveal 1 card in the top of your Deck for each monster(s) in your Graveyard, then, add 1 of them to your hand.|
|Flame Swordsman||Joey Wheeler||Once per turn, you decrease this card's ATK by multiples of 100 to increase the ATK of a Warrior-Type monster you control by that amount.|
|Judge Man||Johnson||Life Sentence (original) / Clear the Courtroom (dub): During either player's turn, you can pay 1000 Life Points to destroy all monsters your opponent controls and inflict damage to your opponent for each monster destroyed by this effect x 500.|
|Robotic Knight||Nezbitt||Super Bombardment (original) / Final Artillery (dub): During either player's turn, you can send any number of Machine-Type Monster Cards from your hand to the Graveyard to inflict damage to your opponent for each sent Machine-Type Monster Card x 500.|
|Goddess with the Third Eye||Serenity Wheeler||Fusion Vision: During your turn, you can discard 1 Spell Card to send Fusion Material Monsters that are listed on a Fusion Monster Card that you control or from your hand to the Graveyard. Afterwards, Special Summon that Fusion Monster from your Extra Deck.|
|Strike Ninja||Duke Devlin||During either player's turn, you can discard 2 cards to activate 1 Set Spell or Trap on the field as if you are the controller.|
|Super Roboyarou||Tristan Taylor||When this card battles with an opponent's monster, you can Set 1 Spell or Trap from your hand. During the Battle Phase only, this card gains 1000 ATK. When an opponent's monster attacks, you can Special Summon this card and make it the new attack target.|
|Jinzo||Leichter||Negate all face-up Trap effects your opponent controls and destroy them.|
|Lord of Dragons||Seto Kaiba||Once per turn, you can pay 500 Life Points to Normal Summon 1 Dragon-Type monster in addition to your Normal Summon/Set.|
|Dark Magician||Yugi Muto/Yami Yugi||During your turn, you can pay 1000 Life Points to activate a Spell effect twice.|
|Kaiser Sea Horse||Seto Kaiba||During your turn, you can perform a Summon or activate the effect for LIGHT monster with 1 less Tribute.|
|Shinato's Ark||Noah Kaiba||This card is treated as a Monster Card (???-Type/???/???/ATK ???/DEF ???). Any monsters sent to the Graveyard can instead be equipped to this card (although they do not occupy Spell & Trap Card Zones). When an opponent's monster attacks while you control no monster(s), you can Special Summon 1 monster equipped to this card in Defense Position for each face-up Attack Position monster your opponent controls. Once per each player's turn, you can banish any number of monsters equipped to this card and gain 500 Life Points for each removed monster. When this card is destroyed by battle, Special Summon 1 "Shinato, King of a Higher Plane" from your hand or Deck and treat it as your Deck Master.|
|Shinato, King of a Higher Plane||Noah Kaiba||When your opponent's Life Points are reduced, increase your Life Points by the same amount. If this monster destroys an opponent monster in Defense Position, halve your opponent's Life Points.|
Reversal: If this face-up card would be affected by a Spell, Trap or Monster effect, you can remove it from the field instead. If you do, you cannot Summon this card again for the remainder of the Duel.
- The Deck Master mechanic is similar to Magic: The Gathering's Commander format, where each player selects a single Commander that can be summoned like any other monster but resides in the unique "Command Zone".
- The Deck Master mechanic is referenced in Yu-Gi-Oh! Duel Links by Tristan Taylor's exclusive Skill, Deck Master Effect: Cyber Commander. Interestingly, "Cyber Commander" was not Tristan's Deck Master in the anime.