Zagreus is a character introduced in the Saint Seiya universe, known for his mysterious origins and connection to the underworld. Often depicted as a formidable warrior with ties to mythological figures, Zagreus brings a sense of intrigue and power to the series. His role includes challenging the main protagonists, testing their resolve, and adding depth to the mythos of the Saints. Zagreus is significant for his unique abilities and the complex moral dilemmas he presents to the heroes.