Mastermind - Rank 4 in the House of X's leadership, a Mutant with the power to telepathically create illusions. Named Jason Wyngarde, he originates from a long-lived English bloodline with roots in nobility. Because of this, he grew up in the lap of luxury, where his every desire was satisfied with either money or servants, and became a cruel and domineering individual as a result, especially once his mutation activated in his early teens, upon which he tormented his servants with nightmarish visions whenever they displeased him. As he grew into an adult, he was eventually invited to join the Hellfire Club, an elusive organization of billionaires from all over the world, a secret cabal of sorts, dedicated to influencing the world through wealth and power. It was via these connections he managed to marry a beautiful, blonde-haired woman and have a daughter, Emma, who he treasured immensely. Amongst the Hellfire Club, he continued to participate in perverse distractions and cruel and sadistic activities, enjoying his life as Mastermind, eventually becoming the Black King and second in command of the Hellfire Club in general. His only fellow Mutant at the time was the young Sebastian Shaw, one of the Black Knights and a member of the long-lived Shaw family that was a part of the club for centuries. Shaw envied Jason, and eventually leaked his position in the club to the House of X, upon which Cassandra and her allies attacked Jason at his home, intimidating him into serving them as their second spy in the club after Shaw. They threatened to kill his wife, expose his cruel deeds, and take his daughter away to an unknown place to mould to suit their own ends. As he both cared for his reputation and his family, he complied with their demands, terrified.

Jason still has a cruel and vindictive personality, and doesn't regret anything he did, but his overall attitude these days is of a man consumed with fear and terror, to the point he is almost pitiable, especially as the other members of the HOX love to intimidate him.

He cares about his family even more than his own reputation, and he cares for his reputation to a vast amount, genuinely loving both his wife and his daughter, and being terrified of what the HOX may eventually do to them. He is filled with constant guilt over selling out the other members of the Hellfire Club to the House of X, and is always looking for ways to escape this situation and the HOX, albeit secretly. He has a taste for fine things, which he still enjoys even in spite of his bondage to the House. His sadistic streak remains, and he still delights in torturing and disorienting people with the illusions he creates. He wears a variety of fine outfits, though when on the job he most often wears a brown coat with a prominent mantle, and elegant black dress pants and a shirt underneath, with a red tie. In addition, when he needs to boost his powers, he puts on a purple, angular mask over his face covered in glowing red, technological eye markings. Despite being rank 4, he has no actual authority in the HOX, and his rank instead indicates his value. This mask has NRV Technology, a type of technology intended to aid psionic manifestation, and allows him to create stronger and more convincing illusions at the cost of potential nerve damage the longer it is used. He has brownish black hair that's curly and bushy, as well as as a mustache and prominent sideburns, but no goatee. His face has an elegant if manly appearance, and his ESP is cloudy and light green. His eyes are light green and have a cloudy texture in the irises, but otherwise can pass off as somewhat normal.