Yami Yugi, also referred to as the Nameless Pharaoh, is the spirit of Pharaoh Atem who has been sealed in the Millennium Puzzle.

Together with Yugi, he holds the title "King of Games", by winning in the Duelist Kingdom, Battle City, Grand Championship and Battle City V2 tournaments.

After Yugi Muto solved the Millennium Puzzle, Yami Yugi resided in Yugi's body and would take possession of it when Yugi or his friends were in danger. After Yugi became fully aware of Yami's existence, Yugi could voluntarily give control of his body to the Pharaoh; occasionally before one would give control to the other, they would, as souls in the mind of the one controlling Yugi's body, converse with each other, usually about their options of what to do when in difficult situations.