Yugi Mutou (Japanese: 武藤 遊戯, Hepburn: Mutō Yūgi; also spelled Muto or Moto) is a fictional character and the main protagonist of the Yu-Gi-Oh! manga series created by Kazuki Takahashi. Yugi is introduced as a teenager who is solving an Ancient Egyptian artifact known as the Millennium Puzzle, hoping that it will grant him his wish of making friends. After solving the Puzzle, Yugi revives an ancient spirit initially known as Dark Yugi (闇遊戯, Yami Yūgi; Yami Yugi in the English anime); the spirit is later revealed to be that of the pharaoh Atem (王（アテム）, Atemu). Over the course of the series, Yugi forms friendships with the supporting cast, interacts with Atem, and learns about his past. Besides the original manga, Yugi has also appeared in anime adaptations, films and video games based on the franchise. Throughout his appearances, his signature Duel Monsters card is the Dark Magician.

Yugi was created as a weak, young man who is interested in games and becomes a hero when playing them. According to Takahashi, through this trait, Yugi emphasizes the series' themes; friendship and the enjoyment of games. Atem was created as a hero who would appeal to young children through his strong characterization.

Critical reception to Yugi has been mixed; some writers found Dark Yugi to be too dark for the series, but others praised the development of both him and Yugi. His role in movies, mostly The Dark Side of Dimensions, was also praised for featuring a more mature version of him.

Kazuki Takahashi had always been interested in games; he was obsessed with them as a child, an interest which he maintained as an adult. He believed games made players into heroes, and decided to base the Yu-Gi-Oh! series around these games with this idea as the premise. He depicted these themes through Yugi, a weak, childish boy who became a hero when he played games. Friendship is another major theme of Yu-Gi-Oh!; Takahashi based the names of the two major characters, "Yūgi" and "Jōnouchi", on the word yūjō (友情), which means "friendship". Henshin (変身, Henshin; lit. Transform), the ability to turn oneself into something or someone else, is something Takahashi believed all children dream of. He considered Yugi's "henshin" Dark Yugi, a savvy and invincible player of games, to appeal to children.

Takahashi also believed that modern society focuses too much on winners and losers. He stated that both Yugi and Katsuya Jonouchi (Joey Wheeler in the English anime) had more potential as characters because they focus on enjoying games rather than aiming to win. He also felt that Dark Yugi and Seto Kaiba are weaker characters despite the former's heroic traits. As a result, he believes Dark Yugi is at his best when he is being supported by the rest of the cast.

According to Takahashi, Yugi and Kaiba are rivals, and they are not close friends. He believes, however, the most important part of their relationship is before Yugi's duel against Marik's alter-ego. Before the game begins, Kaiba passes Yugi a card that could help him in the game. This scene felt like one of the most difficult scenes to write because of the pair's rivalry.

Yugi was given a hairstyle that would fit the style of shōnen manga, and both Yugis had the same hair, even though Takahashi initially considered giving them different hairstyles to convey different personalities. Takahashi described the hairdo as "an open hand with hints of a dried autumn leaf." The colorized versions initially used red to show emphasis, though Takahashi later used magenta in place of red to make it easier to shade the hairstyle. The little Yugi form was given a round style of eyes to convey a softer personality, while Dark Yugi had a contrasting facial style to show that he has a different personality. Atem was derived from Tutankhamun.

Megumi Ogata voiced Yugi in the first anime adaption of the manga, with Shunsuke Kazama replacing her for the following one. Dan Green voiced both Yugi and Dark Yugi in U.S. anime episodes. Ogata recalls that the director chose her to voice Yugi and told her, "I can feel the scent of darkness from you" which she believes refers to Yugi's anti-heroic alter-ego. This work was raised from scratch when Kazama had no experience as a voice actor and did not know how to do it. Due to the latest movie taking place after the finale, Kazama portrayed him as being more mature. Green has used two voice pitches for Yugi and Dark Yugi's voices and enjoyed the parodies his work led to, such as an abridged series.