Esteban Diablo was born in early ninth-century Spain, the son of a nobleman. Curious and inventive by nature, the restless young man was fascinated with the ancient science of alchemy. Using funds borrowed from his inheritance, Diablo roamed Europe in search of documents and artifacts of ancient alchemy, as well as rare potions and herbs with which to experiment. Within a decade, he became the world's greatest living authority on alchemy, having discovered or concocted countless potions with bizarre properties. Haughty and cunning, Diablo began to put his alchemical knowledge to use for personal gain.
Journeying to Transylvania to investigate its legendary secrets, Diablo settled there and established permanent laboratory facilities. Under suspicious circumstances, he acquired a spacious castle and began work. Although most of his potions' effects proved transitory, Diablo discovered an elixir that could retard aging. Drinking it, he embarked on a reign of terror over the surrounding Transylvanians, until a mob of villagers caught him unaware and imprisoned him in a massive crypt. Diablo was trapped there until the 20th century, when he mesmerized the Thing of the Fantastic Four to free him. Not having aged appreciably during his century of confinement, Diablo began to plot his alchemical conquests anew. He has plagued humanity on numerous occasions, most frequently opposed by the Fantastic Four.
