Mahaado is one of the Chosen Priests in the Memory World arc. He is the second holder of the Millennium Ring. He is the captain of the tomb guards, a sorcerer, and one of the Pharaoh's most loyal servants. He teaches the apprentice mage Mana.
Mahaado is one of the few who knows the truth of the creation of the Millennium Items. This and his office puts him at odds with Thief King Bakura, who robs the tomb of the Pharaoh's father, Akunamkanon. He takes it as a personal blow to his honor and goes to fight the Thief King alone.
Mahaado's Magician of Illusion is no match for Bakura's Diabound and Mahaado loses and is sliced through with a swinging blade. His final act in life is to use his heka to cast a spell that combines his soul with his Ka, turning him into the Black Magician (Dark Magician). As the Black Magician he remains faithful to his pharaoh, Atem, and his pharaoh's incarnation, Yuugi. In the end, Bakura ends up with the Millennium Ring and Mahaado the person ceases to exist, reincarnated into Pegasus's Duel Monsters game as a monster.