Japanese manga (comic book) of the late 20th and early 21st centuries that features an ordinary high-school student, Yugi Mutou (Yugi Moto), who assumes mystical powers when playing a mysterious card game.

When blond, spiky-haired Yugi, a weak and unassuming teenager, solves the mysterious Millennium Puzzle, he is granted special powers that are activated when he plays games. Transformed into his alter-ego, Yu-Gi-Oh (“King of Games”), he finds himself engaged in Shadow Games, which change into combat against evil superhuman opponents. The most significant of these is Duel Monsters, a character-card game modeled (within the story line) after an ancient Egyptian invention.

Yu-Gi-Oh! was created by Japanese manga author-illustrator Kazuki Takahashi and began appearing as a regular feature in the magazine Shonen Jump in 1996. While early segments featured a variety of different games, the reaction of teenage fans to Duel Monsters was overwhelming, inspiring Takahashi to create a real-life version, wherein players would pit the numerically valued fighting abilities of trading-card characters against each other. Following in the footsteps of the massively successful Pokémon trading-card game, Yu-Gi-Oh! became a national and ultimately worldwide sensation, spawning several animated television series and a feature film, along with a vast array of licensed merchandise.

The card game and television episodes debuted in the United States in 2001. The ordinary Yugi, who was empowered by game play to be a greater version of himself, was an appealing hero to young fans. Although a successful series of video games was launched, Yu-Gi-Oh! was most successful as a card game that focused on face-to-face card play and social interaction. Nonetheless, many parents' and teachers' groups expressed concern at the intrinsic violence of the Yu-Gi-Oh! universe, just as they had for the Pokémon product line.