[2] The name and visual appearance of Jason Wyngarde as he appears in the Dark Phoenix Saga and later stories was originally based by artist John Byrne on that of British actor Peter Wyngarde, best known for playing Jason King, and who also played the leader of the Hellfire Club in an episode of The Avengers.

[3] Nothing is known of Jason Wyngarde's life before joining the Brotherhood of Evil Mutants, except that he was a carnival mentalist.

With Mastermind's help, the Brotherhood takes over Santo Marco, a fictional South American country, with an illusion of thousands of soldiers.

He attempts to court his teammate Scarlet Witch, but his advances seem driven more by an unsatisfied need for love than by any true feelings for her, and she repeatedly spurns him.

[13] Then, he manipulates her through the use of his own powers and a mind-tap mechanism created by Emma Frost, which he uses to project his illusion directly into her mind, causing her to believe she is living out the life of a Victorian aristocrat who was married to Jason Wyngarde (Mastermind),[14] and was the Black Queen of the Hellfire Club.

Instead of binding Phoenix to him forever, as Mastermind had hoped, the shock of Scott's psychic "death" breaks her free from his control.

[18] He disrupts Wolverine's wedding by psionically compelling his betrothed, Mariko Yashida, to reject him and open up dealings with the criminal underworld.

[19] He manipulates the X-Men into thinking Cyclops's fiancée, Madelyne Pryor, is the reincarnation of Dark Phoenix, hoping to goad them into killing her before he reveals the truth.

Before he succumbs, he asks Jean Grey's forgiveness for what he did to her in an attempt to gain control of the almighty Phoenix Force within her.

Magneto, who had been drawn to the location of the accident by her magnetic pulse, had Mastermind use his illusionary powers to re-write Lorna's memories of that day, since he believed that she was not ready for her abilities or the life he could offer her, leaving her to believe that her parents died in a plane crash when she was an infant.

Teaming up with Mrs. Gwynn who offers the sisters power in exchange for their help, they attempt to track down Pixie after being kidnapped by Saturnine.

[volume & issue needed] In the alternate timeline seen in the 2005 storyline House of M, Mastermind is mentioned to be a business rival of Tony Stark.

In contrast to his appearance in the mainstream Marvel universe, here is a lanky, white-haired, man with sunglasses and a ponytail.

[41] In the alternate universe seen in the 2009 miniseries X-Men: Noir, Wyngarde appears as a member of Eric Magnus's Brotherhood of Mutant detectives in NY.

[volume & issue needed] Mastermind appears as a playable character in Lego Marvel Super Heroes, voiced again by Travis Willingham.