Those that stayed and watched the post-credits scene of X-Men: Apocalypse know that there is a very real evil on the way in the future of the X-Men franchise. While the special tag never says his name explicitly, it does make it very clear that we will soon see the heroes of the comic book movie series face off against the deadly villain known as Nathaniel Essex a.k.a. Mister Sinister. It was certainly an exciting reveal for fans of the genre... but for those who have no idea who the antagonist is, it's pretty meaningless.
Fortunately, for those of you who fall into that camp, we're here to help you out. In order to give you a baseline understanding of who Mister Sinister is and what we can expect from him in future X-Men movies, we've put together this list of bullet points. After reading, you should be just as excited for the character's big screen debut as those who have been reading about him for the last 29 years. Speaking of which...
Mister Sinister made his debut in 1987
In the late 1980s, writer Chris Claremont and artist Marc Silvestri got a bit tired of constantly returning to Magneto and the Brotherhood of Evil Mutants as antagonists for the stories they were writing in X-Men comics. So when it came around to writing Uncanny X-Men #221 for release in September 1987 (part of the "Mutant Massacre" storyline), they took the opportunity to introduce a whole new kind of baddie of the mutant heroes. His part in the issue is brief -- merely shown in the first few pages berating his team of mutant assassins known as the Marauders -- but in the larger arc he would ultimately establish himself as a formidable force with which to be reckoned. It wasn't until 1996 and the limited series The Further Adventures of Cyclops and Phoenix that his full backstory was explained.
Mister Sinister is a scientist
Born in the early 19th century, Nathaniel Essex was a biologist working around the time that Charles Darwin began spreading around his theories about evolution -- and it wound up being research with which Essex became completely obsessed. He endlessly not only contemplated about the incredible potential resting in the genetics, and the idea of creating the perfect human, but even conducted his very own experiments in the field. Unfortunately for those around him, the man who would become Mister Sinister felt that the work he was doing was far away more vital than any societal laws, morality or codes of conduct, which brings us to our next point about this character...
Mister Sinister is completely crazy
Scientists have surely been known throughout history to bend certain rules in their work in order to try and achieve success, but Nathaniel Essex most certainly is what could be considered an extreme example. The reason he first hooked up with the aforementioned Marauders is because he found himself in need of subjects for his experiments, and the group of killers didn't take issue with the idea of kidnapping homeless people and bringing them to the lab. Disturbingly enough, this wasn't the craziest thing he did before officially becoming Mister Sinister, however. Instead, that medal belongs to the time he felt it was perfectly reasonable to dig up his dead son (who died due to birth defects) and do a bit of work on him, much to the horror of his wife, Rebecca Essex. It was on Rebecca's deathbed that she gave Essex his new name, as his pleas for understanding and forgiveness were met with the line, "To me, you are... utterly... and contemptibly... sinister!"
Apocalypse gave him his powers and made him immortal
In the post-Days of Future Past timeline in the X-Men franchise, it's cultists who wind up resurrecting the ancient mutant Apocalypse -- but in the comics Mister Sinister is one of the key people to have accomplished this feat. The two villains first met back in 1859, with Apocalypse convincing Nathaniel Essex to ignore the complaints and protests of his wife and continue his disturbing research in genetics. Essex recognized En Sabah Nur as the first mutant in what would become the emerging species known Homo superior, which added clear motivation to his work. Following the rejection and death of his wife, Essex turned to Apocalypse, and the scientist went through a torturous process to be transformed into the human mutate who would be known as Mister Sinister. He was given gifts like telepathy and telekinesis, but his most important power is that he can control every cell in his body -- which lets him shapeshift and prevents him from aging or being hurt, essentially making him immortal.
Mister Sinister has orchestrated mass murders of mutants
Remember back in the first section when I wrote about the Mutant Massacre storyline in X-Men comics? Well, that bit of violence and bloodshed in the Marvel Universe happened because of an order made by Mister Sinister. The specific "mutants" in this arc are those who are part of a group known as the Morlocks -- who live both literally and figuratively underground - and the individuals who carried out the massacre were the previously mentioned Marauders (including Sabretooth, Vertigo, Riptide, and Scrambler amongst those present). By the end, hundreds were killed -- all because Sinister sensed his genetics work in the Morlocks and was unhappy about the unapproved proliferation of this research.
Mister Sinister is obsessed with the Summers bloodline
The Summers family -- which includes key characters like Scott Summers a.k.a. Cyclops, his wife, Jean Grey, and his brother, Alex Summers a.k.a. Havok -- is an important one in general in the history of X-Men comics. That being said, Mister Sinister has his own particular and personal fascination with the clan. This began all the way back when Scott Summers was a young orphan living in a Nebraska orphanage, and Sinister actually managed to manipulate the young mutant's life from that point forward. He would even wind up having a key role in the birth of Cyclops' first son... which brings us to point number seven!
Mister Sinister has a huge hand in Cable's origin story
Those of you who have read my guide about Cable will find some of this familiar. One of Mister Sinister's many attempts to mess with Cyclops' life involved the creation of Madelyne Pryor -- who would become both Cyclops' wife, and the mother of Nathan Summers, a.k.a. Cable. Sinister created Madelyne using Jean Grey's DNA with the sole purpose of wanting her to have a child with Scott Summers and give birth to a child. This young boy's destiny was established to kill Sinister's former ally, Apocalypse, and it would be his mission in life even after being sent away from his parents to live in the future.
Mister Sinister is a big part of Gambit's life too
Fans largely recognize Mister Sinister for his connection to the Summers family, but he has been a key figure in the life of Remy LeBeau a.k.a. Gambit as well. The two men first met when Gambit was in his teens, and Sinister was using his Dr. Nathaniel Essex moniker as cover. Sinister hired the young thief to break into the Weapon X facility to get back his stolen diaries -- and this wound up being quite an adventure for Gambit, as he actually witnessed the escape of Wolverine. After looking at the work, Remy decided to not deliver the work back to Essex, deeming it too dangerous -- but it wouldn't be their last encounter. Bringing everything full circle, Gambit was actually a key figure in the orchestration of the Mutant Massacre, as he agreed to assemble the Marauders and give them information about the Morlock's home in exchange for help controlling his mutant abilities.