Diablo was born in Spain in the 9th century. He sold his soul to the demon Mephisto for a longer lifespan than a normal human. He then went to Trannsylvania and set up a secret base there but he soon was captured by the villages and burried him in a stone crypt.

Return

The Fantastic Four had a holiday in Trannsylvania. A man named Baron Hugo told them about Diablo and the ancient cockpit which burried him. Diablo communicated with the Thing and offered him a deal. The deal was if the Thing would liberate Diablo from his inprisonment, he would give him the cure of his ungly form and to make the Thing human again. The Thing agreed and went to the stone crypt and freed Diablo. Diablo proposed a new deal with the Thing saying that he would give him the potion in exchange for the Thing's service. The Thing accepted the deal.

The Fantastic Four discovered that Ben had been working for Diablo and tried to force Ben from his service with Diablo. Ben refused to leave with the Fantastic Four which caused the other three members of the Fantastic Four to desert Ben.

Diablo eventually sold his chemicals to the world. His chemicals were effective and useful which made him famous and wealthy. He then began to gather a group of loyal followers and empowered them with his chemicals. Mr Fantastic studied the chemicals Diablo made and concluded that Diablo's chemicals only worked for a short period of time. Diablo, realising that his secret had been exposed to the public, used his loyal followers and attempted to conquer the world.

At that time, the potion Diablo gave to Ben was beginning to wear off. Once again back to the abomination Ben never wanted to be. The Thing, angered that he had been fooled by Diablo, wanted revenge on Diablo. He broke into Diablo's castle and tried to kill him but he failed and Diablo imprisonned the Thing in an unbreakable glass prison cell. The Fantastic Four also went into the Diablo's fortress and tried to stop Diablo but instead were also imprisonned in the same type of prison cells which Diablo used against the Thing. The Thing broke free from the cell and chased Diablo. Diablo was very afraid and tried to run away from the Thing. The Thing squashed a steel suit into a steel ball and hurled the ball towards Diablo. Diablo escaped from the metal ball and hid inside the crypt in which he had been imprisonned. The Fantastic Four trapped him in the crypt once again and strengthened the crypt.

Diablo's Second Return

Diablo used his chemicals and broke free from the crypt. He wanted to kill the Fantastic Four for imprisonning him again. He met a scientist called Dr Gilbert and both of them worked together as partners. Both of them succeeded in animating the Dragon Man and Diablo tried to use it against the Fantastic Four. The Dragon Man betrayed Diablo and both of them were taken to the depth of a frozen lake and was then lost in time.

Alternate Universe's

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Earth-1610 (Ultimate Universe)-In the Ultimate Universe Diablo's real name is Menendez Flores and also goes by the aliases Dr. Diablo, El Diablo and Maestro. He was born in 15th century Genoa, Italy and taught himslef alchemy, herb lore and 15th century science. He first appeared in Ultimate Fantastic Four #39 (2007).