Diabolik is the titular charcater of the series. Thief in profession, his speciality is to steal especially valuable jewelry or large sums of money. Despite carrying out an illegal fair, Diabolik has healthy roots and ethical principles (honor, protect the weak, the sense of friendship and gratitude, respect for noble souls), and therefore hates the Mafia, drug dealers, moneylenders and torturers. Diabolik certainly has a name and a surname, but nobody, not even he knows. In "Diabolik, who are you?", We learn that our protagonist, still in its infancy, is the only survivor of a shipwreck and is saved by the men of a certain King, head of a powerful criminal organization that has its based on an island far from any route. Diabolik grows among offenders of any kind, without being given any of them in particular, but learning from each expert. It is thanks to the teachings of Dr. Wolf, the head of the chemistry lab, realized that our first of his famous masks.
Take the form of the King himself, after having killed and robbed, Diabolik escapes from the island to start his new and unstoppable criminal activity. He would choose his name, inspired by that of a deadly black panther that King killed and embalmed. Only recently we learn that, after escaping from the island and before reaching Clerville, he spent a period of time in the East to improve some of his knowledge. Even if the state of Clerville abolished the death penalty for Diabolik, it decided to make an exception and in case of capture he will be guillotined immediately.