He’s one of the X-Men’s most notable foes, and he’s just made a big comeback in the Disney+ animated series X-Men ’97. Few villains have been as much of a thorn in the side of Charles Xavier’s students as the mysterious Mister Sinister. Here is the century-long history of one of the chief architects of the Marvel Comics mutant’s misery.

Mister Sinister reveals himself to the X-Men in the third episode of X-Men '97.
Marvel Animation

Mister Sinister’s First Marvel Comics Appearance

Two of the X-Men’s greatest foes made their debuts in the 1980s. One was the immortal mutant Apocalypse, and the other, the mad geneticist called Mister Sinister. This pale-faced, red-eyed, and razor-toothed villain made his first official appearance in 1987’s Uncanny X-Men #221, kicking off the seminal “Fall of the Mutants” Storyline. However, from behind the scenes, his first major move against the X-Men happened a year earlier, when they revealed him by name as the mastermind behind the infamous Mutant Massacre, in 1986’s Uncanny X-Men #211.

Marvel Comics

Mister Sinister and the Mutant Massacre Saga in X-Men

Marvel Comics

The “Mutant Massacre” storyline was where the X-Men first felt Sinister’s evil, though we would not formally meet him for another year. In this story, a band of vicious mutants called the Marauders slaughtered the mutants who lived under New York City in its sewer tunnels called the Morlocks. These Morlocks were created by stolen science of Sinister’s, and he considered them an abomination to be eliminated. The Marauders were organized by future X-Man Remy LaBeau, a.k.a. Gambit, who felt tremendous guilt about his role in the massacre for the rest of his life. Following the event, Sinister stepped out of the shadows and became one of the X-Men’s most mortal foes, fighting them for years. But he had been in the wings since long before Xavier formed the X-Men.

The Origin of Mister Sinister

Marvel Comics

The original Mr. Sinister was born in Victorian England, as Dr. Nathaniel Essex. When his first child passed away due to several birth defects, the brilliant biologist wanted to discover the source of human mutations. In fact, it became his singular obsession. He identified the random element in the human genetic code that caused mutations, which he called “the Essex factor,” later shortened to “the X factor.” But the scientific community of the time ridiculed him, eventually making Essex an outcast. But it didn’t deter his work, and he paid a London street gang called the Marauders to kidnap disfigured people and bring them to him for experimentation.

Marvel Comics

At one point, the Marauders encounter the ancient mutant En Sabah Nur, a.k.a. Apocalypse, who had just awakened from his centuries-long slumber. He was so impressed by Essex’s work with mutations he offered him immortality, and the gift of incredible powers, if Essex used his knowledge in Apocalypse’s service. At first, Essex said no, but eventually the death of his wife Rebecca and his second child cemented his descent into amorality. Learning of his twisted experiments, his wife’s final words to him called him “sinister,” which he then took as his name after Apocalypse enhanced him.

What Are Mr. Sinister’s Marvel Powers and Abilities? Is Sinister a Mutant?

Marvel Comics

Altered at a cellular level by Apocalypse, and his access to Celestial technology, Sinister now had enhanced durability and an extended lifespan. Over time, he absorbed the powers of other mutants via sampling their genetic material. Among these powers are telepathy, telekinesis, superhuman strength, energy projection, and control of his body at the molecular level, giving him shapeshifting powers. He also rapidly heals from most injuries. His own innate scientific genius allows him to be a master at cloning, which he put to horrible use in the following decades.

Mister Sinister vs. Apocalypse

Marvel Comics

Apocalypse gave Essex incredible powers, but the latter quickly realized that En Sabah Nur was too dangerous and would likely destroy the world. He knew he had to engineer a mutant powerful enough to take him down. He believed that mixing specific bloodlines could produce a mutant powerful enough to destroy him. Sinister spent much of the 20th century attempting to bioengineer that very being. In Russia, he encouraged Gregori Rasputin to have as many children as possible, ultimately resulting in Colossus and Magik. Neither was strong enough to defeat Apocalypse.

Nathaniel Essex joined Hitler’s Third Reich in the ‘30s, and at Auschwitz, he experimented on children, including a young Magneto, possibly expanding his powers to what they ultimately became. After World War II, he embedded himself in the United States government’s Project: Black Womb under a new alias. There, he inserted his genetic material into the children of his fellow scientists. These children included Sebastian Shaw and Charles Xavier. He would later teach a young Xavier at Oxford. However, his biggest “science project” had to do with future X-Men Scott Summers and Jean Grey.

Why Is Mister Sinister Obsessed with the X-Men Leader Cyclops?

Marvel Comics

Sinister’s obsession with Scott Summers goes back to the 19th century. In his early years, he encountered a time-traveling Scott and Jean and marveled at their mutant powers. He discovered their surnames were Summers and Grey, and became obsessed with tracking their bloodlines. In the early 20th century, he opened the Nebraska State Home for Foundlings, an orphanage where he housed discarded children with genetic potential. Two of those children were orphans Scott and Alex Summers. Using the alias Dr. Nathan Milbury, Essex decided that Alex had less potential, and separated him from his brother.

While running the orphanage, Sinister masqueraded as another child named Nate, who was Scott’s only friend. He thought this way was easier to manipulate him. He even gave young Scott his first Ruby Quartz glasses to control his mutant optic blasts. When Scott Summers was almost adopted, Essex arranged for the death of his prospective parents. But Scott later escaped the orphanage, eventually going to Xavier’s School. Fortunately for Sinister, Scott met another Omega-level mutant there named Jean Grey, and they fell in love. Sinister hoped that their eventual union would produce the mutant to defeat Apocalypse once and for all. But Jean’s transformation into the Phoenix and eventual death temporarily halted that scheme. But as always, Essex had a backup plan.

Mister Sinister, Madelyne Pryor, Cable, Apocalypse, and Miss Sinister

Marvel Comics

Sinister created a clone of Jean Grey who he named Madelyne Pryor, and with false memories inserted her into the life of Scott Summers after Jean’s death. They married and had a child, the ultimate goal of Sinister’s centuries-long plan. That mutant child, whom Scott named Nathan Christopher Charles Summers, was named for the fake “best friend” he had at the orphanage, aka Sinister in disguise. The baby Nathan was an Omega-level mutant, so Apocalypse infected the child with a techno-organic virus. He would either survive and become more powerful, or the virus would kill him.

Marvel Comics

After being sent to the future, that child grew up to become the warrior Cable. As Cable, he came back in time on a mission to defeat Apocalypse, which he did, fulfilling Sinister’s decades-long plans. Apocalypse eventually returned, however. Despite seemingly dying several times himself, Sinister kept returning as well. He kept transferring his consciousness into new clone bodies of himself, including a female one, Miss Sinister. The assumption was always that the Sinister the X-Men had fought for years was the original. That, it turns out, was not the full truth.

Mister Sinister and the Mutant Nation of Krakoa

Marvel Comics

Despite years of enmity towards each other, Charles Xavier and Magneto asked Sinister to join them in establishing the mutant nation of Krakoa. Sinister had genetic material on almost every mutant on Earth, something they needed for the Krakoan Resurrection Protocols to give mutants immortality. They even gave Sinister a seat on the Krakoan Quiet Council, which ruled mutantkind. It was during this Krakoan era that Sinister’s biggest secret came to light. The Mister Sinister the X-Men fought for years wasn’t the original Nathaniel Essex, but his clone. Actually, one of four clones made in the late 19th century of the original Nathaniel Essex.

The Truth About Sinister, and His Many Clones

Marvel Comics

We learned during the Krakoan era that the real Essex died in 1895. He made three clones of himself, each believing themselves to be the real Essex, and sharing his memories. The one we know today as Mr. Sinister was a mutant born with an X-gene, one whose powers Apocalypse augmented. A human clone, who believed in homo sapiens’ superiority, became the hateful Mr. Stasis. Another clone, Orbis Stellaris, left Earth to learn about alien technologies. The fourth clone was actually of Essex’s dead wife Rebecca, called Mother Righteous, who wielded magic. Each had a different playing card designation on their forehead, with Sinister’s being a red diamond. The human supremacist clone Mr. Stasis has very nearly destroyed the mutant race with his Orchis initiative. Thus proving that in one form or another, Nathaniel Essex might be mutantkind’s greatest foe.

Live-Action Mr. Sinister Teased in 20th Century Fox Films like X-Men: Apocalypse, Deadpool 2, and New Mutants

Twentieth Century Films

Although most of the X-Men’s main foes appeared in live-action in the Fox X-Men films, Mister Sinister wasn’t one of them. They teased the character at the end of X-Men: Apocalypse, when we saw agents of “Essex Corps” cleaning up blood samples after Wolverine’s bloody rampage. Another tease happened in Deadpool 2, with the young mutant Russell living in the Essex House for Mutant Rehabilitation. In New Mutants’ Dr. Reyes worked for Essex Corporation too. Yet despite all this buildup, we never saw Sinister. This allows for the MCU to actually make Sinister their main villain for their eventual X-Men films without repeating what Fox did.

Mister Sinister in X-Men ’97

Marvel Animation

Before any MCU appearances happen though, Sinister will be the main villain of X-Men ’97 on Disney+, with actor Christopher Britton returning from X-Men: The Animated Series to voice him. He arrives in episode three of season one, “Fire Made Flesh.” We learn he created a clone of Jean Grey, which would produce a mutant child with Scott Summers for him. Once baby Nathan was born, he “activated” clone Jean to bring the child to him.

Hoping to make him stronger, he infected Nathan with a techno-organic virus… one that if he survived, would make him quite powerful. Although the X-Men rescue the child, Sinister escapes. We expect his machinations will continue throughout season one of X-Men ’97. It sure feels like Mister Sinister might soon claim the throne of the X-Men franchise’s most prominent and feared villain.

Originally published on March 8, 2024.