Real name: Jason Wyngarde
Occupation: Former professional criminal, subversive and carnival mentalist
Group affiliation: Formerly the Brotherhood of Evil Mutants and Factor Three, former operative of the Secret Empire II, applicant for admission into the Inner Circle of the Hellfire Club
Base of operations: Mobile at the time of his death; formerly Asteroid M and the Hellfire Club mansion, New York City First appearance: X-Men (Vol. 1) #4 (1964)

Height: 5'10" (normal), 6'2" (illusory)
Weight: 140 lbs. (normal), 190 lbs. (illusory)
Eye color: Gray
Hair color: Gray-black (normal), brown (illusory)

Powers: Mastermind possessed the psionic ability to cast illusions -- causing subjects to see, hear, touch, smell or taste that which did not exist. Also, he could prompt people to see, hear, touch, smell or taste things in ways they naturally would not. For example, he was able to make himself look and sound like a different person, look and feel like a wall or even appear invisible. Mastermind often used his powers to grant himself an illusory handsome appearance. Without artificial aids, he could not limit the perception of his illusions to a single person present among a group.

Weapons: During his psionic enthrallment of the Phoenix Force, an alien being he believed to be the X-Man Jean Grey, Mastermind used a miniature mind-tap mechanism to project illusions directly into the entity's mind and monitor its thoughts -- both over vast distances.

History: Little is known of Mastermind's life until he entered the world war between good and evil mutants. Working as a carnival mentalist, he was recruited by the genetic terrorist known as Magneto. At this time, the self-anointed Master of Magnetism sought to protect his fellow mutants from persecution by conquering humanity and ruling the world himself. Mastermind and the other members of the Brotherhood of Evil Mutants were his allies in pursuit of these goals.

Beneath his illusory exterior, Jason Wyngarde was a master manipulator. Hated and feared by the world outside his mind, he turned to terrorism as a member of Magneto's Brotherhood of Evil Mutants. Rejected by his own kind and robbed of cosmic awareness, he retreated within himself. Mastermind eventually fell victim to the lethal Legacy Virus, making peace with past deeds as the mutant plague claimed his true form.

As a member of the Brotherhood, Mastermind clashed repeatedly with the heroic band of masked, mutant adventurers known as the X-Men. Guardians of mentor Charles Xavier's dream for peaceful coexistence between man and mutant, the latter team continually thwarted Magneto and the Brotherhood. Finally, Magneto attempted to enlist the enigmatic alien being called the Stranger as an ally. Angered, the Stranger transformed Mastermind into stone and transported Magneto to another planet.

Mastermind eventually returned to normal and joined Factor Three, another organization of mutants bent on world conquest. However, Mastermind and his allies teamed with the X-Men to defeat Factor Three's leader after discovering he was an extraterrestrial being.

Following yet another setback as a member of Magneto's Brotherhood, Mastermind was invited to apply for admission to the mutant-dominated Inner Circle of the Hellfire Club, an elite social organization of the world's wealthiest and most powerful figures. To prove his worth, Mastermind sought to use his mutant powers and artificial means to alter the personality of the telepathic, telekinetic X-Man Jean Grey so she would willingly become the Inner Circle's new Black Queen. Unknown to Mastermind, his victim was not the real Jean Grey. A cosmic entity, the Phoenix Force, had duplicated Grey's form and personality. Mastermind succeeded in convincing the false Grey to become the new Black Queen, thus unintentionally triggering the process that soon would transform her into the power-mad Dark Phoenix. Before the latter metamorphosis was complete, the Phoenix Force broke free of Mastermind's control and opened his mind to the myriad psionic sense impressions it had received from the cosmos. Unable to cope with the magnitude of it all, Mastermind fell into a catatonic state. The Inner Circle, of course, rejected his application for membership.

Mastermind ultimately returned to normal, but remembered his brush with galactic greatness. Tormented by his inability to experience the glory of the cosmos as he had perceived it, he set out to exact revenge on Grey's teammates. First, Mastermind induced Mariko Yashida to call off her marriage to the feral Wolverine. He then took aim at team leader Cyclops. Mastermind caused Scott Summers and his fellow X-Men to believe that Madelyne Pryor, whom Cyclops loved, was Dark Phoenix. He hoped to crush the X-Men's spirits by thus manipulating them into killing Pryor. But the team discovered his deception and thwarted his efforts. Mastermind later tried to tap the power of Rachel Summers, the daughter of Scott Summers and Jean Grey from an alternate timeline. This attempt also failed, and Mastermind was imprisoned under the delusion that he had achieved cosmic awareness.

Later, it was revealed that Mastermind had contracted the terminal mutant plague known as the Legacy Virus. On his deathbed, he made peace with Jean Grey and told her she was the woman he had come closest to truly loving. The villain's daughter -- Martinique Jason, who possesses similar powers -- has since adopted the guise of Mastermind.