Yusei Fudo/ Signer

One of the Signers, and the current King of Duelists. He is known for and respected by many other characters in the show for his genius style of dueling, his considerable duel skill, and his cool and clever personality. He uses a Duel Runner, which is called the Yusei Go. "Let's rev it up!" is a common catchphrase that he uses when he summons a Synchro Monster.
Yusei is usually depicted as being serious, calm and clear-minded; even in very dangerous situations. Due to this he rarely acts on impulse and usually thinks things through before he plays any cards, always trying to stay one step ahead of his opponent. This is made obvious during his duels, as he regularly visualizes card flowcharts in his mind in order to devise his strategies. He is also very close to his friends and very hesitant to put them in harm's way. In the English version, Yusei has had a fear of insects ever since a cockroach nested in his ear, as said by Nervin. He was however able to conquer this fear after his Duel against Lenny.
Yusei was born in the Tops area of New Domino City. His parents were lead developers for the Ener-D Reactor. Dr. Fudo named his son Yusei after the Planetary Particle (Yuusei Ryuushi), as he wished for Yusei to be able to connect people with bonds. As the Zero Reverse was about to take place, before dying, Yusei's father placed Yusei in an escape pod, saving him from the disaster that would follow. Yusei's parents were both killed in the Zero Reverse and Yusei was sent to an orphanage in Satellite, where he was fostered by Martha. Growing up he was interested in auto shop and Jack defended him and his friends from bullies.
Yusei grew up in Satellite, where he befriended Kalin Kessler, Jack Atlas, and Crow Hogan. As residents of Satellite, they were made to do labor for the residents of New Domino City and denied many luxuries which were enjoyed by the residents of New Domino.

Jaden Yuki (Judai Yuki)/ The Supreme King

Jaden loves dueling and believes that all problems can ultimately be solved through it. He keeps going no matter how hard things get or how hopeless it seems, with a few exceptions (though it doesn't take much encouragement for him to start fighting again), although he does sometimes doubt himself. He always shows respect towards his opponents, with a few exceptions, even complimenting them during a Duel. Jaden shows little interest in areas outside of Dueling, which extends to his classes. When he chooses to attend them, he generally falls asleep. Despite his low grades, he is still regarded as one of Duel Academy's best Duelists. However, this attitude eventually shows itself as one of his greatest flaws, and causes him to be targeted by Mr. Stein. He shows a lack of knowledge in areas outside of Dueling, even showing in one instance that is unaware of what the term "fiancee" means, and forgetting that the holographic water will not drown him in another. He also seems ignorant of the dislike that other individuals have for him, as despite the obvious tension between the two, he considers himself to be good friends with Chazz Princeton. His carefree attitude and lack of thought gets him into trouble on occasion, such as when he handed the Satellite Keys to Sartorius and still expected the latter to Duel him before using them. He occasionally shows signs of intellect, such as determining that Titan's Shadow Game was a farce.
Jaden has a close bond with his cards, to the point where he has no problem with an opponent insulting him, but is angered when they insult his cards. Jaden is also fiercely loyal to his friends, which often results in his risking his life to save them. This is ultimately exploited by Yubel and Brron, who drive him to the brink of despair via the elimination of his loved ones, which weakens him enough to be possesed by the spirit of his past life. After being freed from the influence of The Supreme King, Jaden shows many signs of depression, and constantly asks himself where he went wrong, and is horrified by what he's done while ruling the alternate dimension. Even after the sacrifice of Aster Phoenix, Jaden is still unable to regain his resolve. When confronted by Guardian Baou, Jaden even resigns himself to be killed at the same spot his friends were sacrificed. His resolve is stirred by the arrival of Bastion Misawa, who reveals that Yubel is responsible for everything that's transpired. Wanting revenge, Jaden defeats Baou and moves on, witnessing the death of Zane Truesdale, which stirs him to continue.

Yugi Mutou/ Nameless Pharaoh (Yami Yugi)

In the first episode of the English anime, Yami defeats Seto Kaiba and uses his power to break his mind. Kaiba is able to recover.
He is slightly reserved, as he doesn't reveal his existence to Yugi or his friends. After Yugi admits to thinking "another Yugi" exists inside him, his friends become aware of his existence and accept him as a friend.
Yami's pride is his greatest strength and weakness. Initially he refuses to lose games, without considering the consequences. This has caused him to almost kill Seto Kaiba by attacking him while he stood on a ledge and would fall if his monster was attacked and Yugi would have won the duel (in the Japanese version, Kaiba threatened to commit suicide should he lose). Yugi holds him back from such acts at times, although not always successful. Yugi becomes afraid to let Yami out for a while, because of the harm he could cause. During his duel with Rafael, Yami, albeit with great hesitation, eventually ignored Yugi's objections and used the Seal of Orichalcos rather than lose. Ironically, it was this action and Yami's subsequent corrupt actions during the duel would lead to one of his few defeats and the capture of Yugi's soul by Dartz. Yami expressed great grief and guilt following the battle due to Yugi's willingly suffering, which were because of Yami's actions. Learning how to lose becomes an essential part of Yami's journey, which he is tested in the Ceremonial Battle.
Yami is also wise and intelligent. He knows all the rules and details of how the game is played. Yami is also capable of reading the ancient language of the Egyptians, figuring out the riddles or clues and what they mean.

Yugi possesses the Millennium Puzzle, which allows his body to bear host to the spirit of the Puzzle, Yami Yugi. Yugi was initially unaware of his existence and control of Yugi's body would involuntarily shift to Yami, when Yugi or his friends are wronged.
Yugi is part of a close-knit group of friends: Joey Wheeler, Tristan Taylor, and Téa Gardner as well as Ryo Bakura and (In some cases) Mokuba Kaiba. Miho Nosaka is also one of Yugi's friends in the first series anime. Yugi's friends often cheer him on from the sidelines, and Joey has dueled at his side. Yugi has been friends with Téa since childhood and only sees her as a friend. Téa has been shown to have feelings for both Yugi and Yami Yugi.