Evolto Kamen, known as Kamen Rider Evol in his Black Hole Form, is the primary antagonist in the series Kamen Rider Build. He is an extraterrestrial being who manipulates events from the shadows to achieve his goal of destroying worlds using the Pandora Box. In his Black Hole Form, Evolto attains his most powerful state, harnessing the destructive ability to manipulate black holes. His intelligence, cunning, and overwhelming power make him a formidable foe for the protagonists.