Atem is a central character in the Yu-Gi-Oh! anime series, known as the ancient Egyptian Pharaoh whose spirit resides in the Millennium Puzzle. Initially referred to as the 'Nameless Pharaoh,' he regains his memories and true name as the story progresses. Atem is wise, courageous, and has a strong sense of justice, often aiding Yugi Mutou and his friends in duels against evil forces. His leadership and dueling skills are pivotal throughout the series, culminating in his eventual journey to the afterlife.