The Millennium Eye (
Shadi placed the Millennium Eye into Maximillion Pegasus's left eye (in the manga, Pegasus's eye was cut out before the item was forced into the emptied socket). After having it successfully in place of his left eye, Pegasus saw his deceased wife Cecelia Pegasus for a fleeting moment. To be inconspicuous, Pegasus then wore the eye for the rest of his life (normally hidden under his hair). Wanting to bring that image of his wife back, Pegasus used the Millennium Eye's power to read minds during his first duel with Yami Yugi. After the duel, Pegasus used the Eye's power to trap Yugi's Grandpa's soul to lure Yugi to Duelist Kingdom. When Seto Kaiba arrived, Pegasus used his Eye's power to trap Mokuba Kaiba's soul. When Pegasus dueled Kaiba, he used the Eye's power to read Kaiba's mind and deck. After Pegasus defeated Kaiba, the former used the Eye's power to take the latter's soul. While the Duelist Kingdom's finals occurred, Pegasus used his Eye's power to look into each duelist's hearts during Yami Yugi's and Mai Valentine's duel and when Joey Wheeler's and Bandit Keith's duel. After Mai surrendered to Yami Yugi and Joey defeated Keith, Pegasus used his Eye's power to "punish" Keith with a Penalty Game (this only happened in the manga). When Pegasus and Yami Yugi dueled, Pegasus used the Millennium Eye's power to read Yami Yugi's mind and strategies until Yami Yugi and Yugi Muto switched places to confuse Pegasus, which worked until Pegasus used the Eye's power to turn their duel to into a Shadow Game which "killed" Yugi's soul. Just when Pegasus used the Eye's power read Yugi's mind, Yugi's friends blocked Pegasus' Eye's power and Yugi used this opportunity to defeat Pegasus, restoring the souls of Solomon, Seto Kaiba and Mokuba Kaiba. Unknown to everyone, Pegasus was also defeated by Yami Bakura, who won the Millennium Eye from him in a Shadow Game; in the manga, Dark Bakura simply took the eye from Pegasus after his loss against Dark Yugi.
Sometime later, Dark Bakura gave the Millennium Eye to Yugi in the manga while Yami Bakura gave Kaiba in the anime after their duel as a lure to get him traveling to where the Pharaoh Atem resided.
It turns out that the Millennium Eye was created 3,000 years prior with other Millennium Items by Aknadin. After its creation, Aknadin himself put on the Eye, sacrificing his left eye in the process, either wishing for his son Seto to become pharaoh which was impossible due to Seto's birth status in the manga or to ward off Zorc Necrophades in the anime.
The Millennium Eye appears on the crown of "Ma'at".
It's primary ability is to peer into the mind of an opponent, allowing the owner to know what he is thinking at all times, no matter what. When he is dueling, the owner can use the Eye to see his opponents cards and strategies clearly, giving him a significant advantage. He can also see their hidden memories and if there is a spirit inhabiting their minds.
Like the rest of the Millennium Items, it can also initiate Shadow Games, materialize the effects of Duel Monster cards, and also, cast illusions, and protect its owner from harm and other magical powers. It can also initiate the Mind Card Penalty Game, where it seals the soul of someone inside a card. Other lesser powers include sensing the location of people of interest.
In the manga, it was said that anyone who wears the eye will be given one wish.
The two known wielders of the the Millennium Eye (Pegasus and Aknadin) share similar traits and stories. Both have lost a loved one that determine their "wish" when they receive the Eye and set a goal involving them that leads to them attempting to obtain all of the Millennium Items to achieve that goal. Also, both are responsible for the form the Shadow Games take in their respective time periods due to what they created based on ancient writing and images (Pegasus creating Duel Monsters and Aknadin creating the Millennium Items themselves).