Yami Yuugi

Yami Yuugi is the spirit of the ancient Pharaoh residing in the Millennium Puzzle. His past is shrouded in mystery. 3,000 (5,000 in the dub) years later, Yuugi Mutou, after trying to solve the puzzle for eight years, awakens the Pharaoh from his slumber, although Yuugi does not realize this until much later in the story. At the end of Duelist Kingdom, the Pharaoh asks Yuugi to help him recover his memories and Yuugi agrees to help him. (Source: Yugipedia)