Dio Brando , later known mononymously as DIO , is a fictional character and a primary antagonist in the Japanese manga series JoJo's Bizarre Adventure written and illustrated by Hirohiko Araki. He is featured initially as the main antagonist of the series' first part, Phantom Blood, and later returns as the main antagonist of the series' third part, Stardust Crusaders, now solely referred to as DIO. In the alternate universe of the series' seventh part, Steel Ball Run, a character named Diego Brando bears resemblance to Dio and appears as a secondary antagonist.