Niccolò[1] "Nico" di Angelo is a fifteen-year-old Italian-born Greek demigod, the son of Hades and the late Maria di Angelo. He is a main character in the Percy Jackson and the Olympians, The Heroes of Olympus, and The Trials of Apollo series of books, and the protagonist of The Nico di Angelo Adventures series of books. Nico is the younger brother of the late Bianca di Angelo and the paternal half-brother of Hazel Levesque. He is known in the Underworld as the "Ghost King"