| Kidmodo DragonShadow Specters · 094 | Shadow Specters | 094 | Super Rare | €0.07 |
| Kikinagashi FuchoRising Rampage · 094 | Rising Rampage | 094 | Common | €0.41 |
| Killer NeedleMetal Raiders · 006 | Metal Raiders | 006 | Common | €0.12 |
| King Beast BarbarosEternity Code · 030 | Eternity Code | 030 | Common | €0.05 |
| King DragunFlaming Eternity · 036 | Flaming Eternity | 036 | Super Rare | €0.33 |
| King FogLegend of Blue Eyes White Dragon · 036 | Legend of Blue Eyes White Dragon | 036 | Common | €0.02 |
| King of Destruction - XexexYu-Gi-Oh! World Championship 2005 prize cards · 501 | Yu-Gi-Oh! World Championship 2005 prize cards | 501 | Ultra Rare | €0.50 |
| King of the Ashened CityPhantom Nightmare · 091 | Phantom Nightmare | 091 | Super Rare | €0.13 |
| King of the BeastsRaging Battle · 086 | Raging Battle | 086 | Secret Rare | €14.87 |
| King of the Feral ImpsLord of the Tachyon Galaxy · 056 | Lord of the Tachyon Galaxy | 056 | Common | €0.08 |
| King of the Skull ServantsThe Lost Millennium · 032 | The Lost Millennium | 032 | Common | €1.04 |
| King of the SwampAncient Sanctuary · 082 | Ancient Sanctuary | 082 | Rare | €0.16 |
| King of YamimadoUnlisted Printings | Unlisted Printings | — | — | — |
| King of YamimakaiMetal Raiders · 074 | Metal Raiders | 074 | Common | €0.14 |
| King PyronTactical Evolution · 026 | Tactical Evolution | 026 | Common | €0.09 |
| King ScarletThe Dark Illusion · 070 | The Dark Illusion | 070 | Common | $0.11 |
| King's ConsonancePremium Gold: Infinite Gold · 019 | Premium Gold: Infinite Gold | 019 | Gold Secret Rare | $0.44 |
| King's KnightElemental Energy · 006 | Elemental Energy | 006 | Rare | €0.02 |
| King's ResonanceBlazing Dominion · 071 | Blazing Dominion | 071 | Common | €0.11 |
| King's SarcophagusAge of Overlord · 058 | Age of Overlord | 058 | Ultra Rare | €2.07 |
| King's SynchroInvasion: Vengeance · 067 | Invasion: Vengeance | 067 | Super Rare | €0.04 |
| King Tiger WanghuPharaonic Guardian · 004 | Pharaonic Guardian | 004 | Rare | €0.99 |
| Kingyo SukuiDuel Overload · 031 | Duel Overload | 031 | Ultra Rare | $0.15 |
| Kinka-byoThe Duelist Genesis · 034 | The Duelist Genesis | 034 | Super Rare | €0.05 |
| KiryuMagician's Force · 009 | Magician's Force | 009 | Common | €0.04 |
| KiseitaiPharaoh's Servant · 046 | Pharaoh's Servant | 046 | Short Print | €0.02 |
| Kishido SpiritMagician's Force · 038 | Magician's Force | 038 | Common | €0.06 |
| Kitchen DragonmaidMystic Fighters · 018 | Mystic Fighters | 018 | Secret Rare | $2.57 |
| Kitsuni KitsunebiCyberstorm Access · 028 | Cyberstorm Access | 028 | Common | €0.03 |
| Kittytail, Mystical Beast of the ForestCyberstorm Access · 096 | Cyberstorm Access | 096 | Super Rare | €0.08 |
| Kiwi Magician GirlYu-Gi-Oh! The Dark Side of Dimensions Movie Pack · 016 | Yu-Gi-Oh! The Dark Side of Dimensions Movie Pack | 016 | Ultra Rare | €0.56 |
| Knight Armed Dragon, the Armored Knight DragonThe Infinite Forbidden · 012 | The Infinite Forbidden | 012 | Common | €0.09 |
| Knight Day GrepherShadow Specters · 038 | Shadow Specters | 038 | Common | €0.05 |
| Knightmare CerberusFlames of Destruction · 045 | Flames of Destruction | 045 | Super Rare | €0.37 |
| Knightmare Corruptor IbleeFlames of Destruction · 017 | Flames of Destruction | 017 | Secret Rare | €0.34 |
| Knightmare GoblinFlames of Destruction · 044 | Flames of Destruction | 044 | Ultra Rare | $1.98 |
| Knightmare GryphonFlames of Destruction · 048 | Flames of Destruction | 048 | Secret Rare | $0.11 |
| Knightmare Incarnation IdleeDark Neostorm · 017 | Dark Neostorm | 017 | Secret Rare | $0.18 |
| Knightmare MermaidFlames of Destruction · 043 | Flames of Destruction | 043 | Rare | $0.24 |
| Knightmare PhoenixFlames of Destruction · 046 | Flames of Destruction | 046 | Super Rare | €0.02 |
| Knightmare UnicornFlames of Destruction · 047 | Flames of Destruction | 047 | Secret Rare | €0.09 |
| Knight of Armor DragonBlazing Vortex · 037 | Blazing Vortex | 037 | Common | €0.13 |
| Knight of LegendSpeed Duel Starter Decks: Match of the Millennium · 02 | Speed Duel Starter Decks: Match of the Millennium | 02 | Common | €0.09 |
| Knight of the Red LotusStardust Overdrive · 032 | Stardust Overdrive | 032 | Super Rare | €3.09 |
| Knight of Twin SwordsUnlisted Printings | Unlisted Printings | — | — | — |
| Knight's TitleYu-Gi-Oh! Reshef of Destruction promotional cards · 002 | Yu-Gi-Oh! Reshef of Destruction promotional cards | 002 | Prismatic Secret Rare | $0.63 |
| Koa'ki Meiru BeetleStardust Overdrive Sneak Peek Participation Card · 1 | Stardust Overdrive Sneak Peek Participation Card | 1 | Ultra Rare | $0.13 |
| Koa'ki Meiru BergzakThe Shining Darkness · 099 | The Shining Darkness | 099 | Secret Rare | $3.70 |
| Koa'ki Meiru BoulderAncient Prophecy · 018 | Ancient Prophecy | 018 | Common | €0.11 |
| Koa'ki Meiru CrusaderAncient Prophecy · 019 | Ancient Prophecy | 019 | Super Rare | €3.28 |