A Victorian-era scientist obsessed with evolution in all its forms, Nathaniel Essex allowed the immortal warlord known as Apocalypse to augment his body and strip him of his humanity. Now, he is Mr. Sinister -- a master manipulator and expert geneticist working to create the most powerful mutant the world has ever seen!

Real name: Dr. Nathaniel Essex
Occupation: Geneticist
Group affiliation: None
Base of operations: Unknown
First appearance: Uncanny X-Men #221 (1987)

Height: 6'5"
Weight: 285 lbs.
Eyes: Shining red, with no visible pupils
Hair: Black

Powers: A brilliant biologist and geneticist, Mr. Sinister is also immortal -- granting him a unique perspective on human evolution. Sinister can manipulate his molecular structure, thus altering his appearance and shape. Also, he possesses superhuman strength and an accelerated healing factor.

Weapons: None

History: As a biologist in Victorian England, Nathaniel Essex developed advanced theories on human evolution. A geneticist of unparalleled genius, he foresaw the coming of Homo superior -- a new breed of man, gifted with strange and fantastic abilities simply by virtue of their cellular makeup. However, his unorthodox experiments resulted in his ouster from the Royal Society. Shunned even by his wife, Essex found an ally in Apocalypse, an immortal mutant who had witnessed firsthand virtually the whole of human history. The merciless warlord transformed the rogue scientist into the ageless being who would become Mr. Sinister.

A Victorian-era scientist obsessed with evolution in all its forms, Nathaniel Essex allowed the immortal warlord known as Apocalypse to augment his body and strip him of his humanity. Now, he is Mr. Sinister -- a master manipulator and expert geneticist working to create the most powerful mutant the world has ever seen!

As Essex, Sinister operated an obstetrics clinic in New York during the late 19th century, secretly studying society's deviants, and influenced the work of Herbert Wyndham, now the master geneticist known as the High Evolutionary. Plotting the course of specific gene pools for more than a century, Sinister discovered that a being of incredible power would result from the union of two young mutants: Scott Summers, known today as the optic-blasting Cyclops, and Jean Grey, the telepath who would come to be called Phoenix. To confirm his findings, Sinister arranged for the boy to be brought to his orphanage in Nebraska, and collected a blood sample from the girl. When Jean appeared to die years later, Sinister used the sampled blood to create a clone, Madelyne Pryor.

Sinister's unflinching obsession with evolution has brought him into repeated conflict with the X-Men, the outlaw band of heroic mutant adventures whose members include Cyclops and Phoenix. Assembling a team of superhuman assassins, Sinister set in motion the massacre of the Morlocks, an underground community of mutant outcasts, simply because he considered them genetically obsolete. The X-Men were able to help some of the Morlocks to safety, and a considerable number managed to escape Sinister's Marauders on their own -- but the majority perished. Sinister himself first fought the X-Men during an invasion of demon mutants he helped create. Later, when the High Evolutionary activated a satellite that stripped all mutants of their superhuman abilities, Sinister overpowered his former student and modified the beam to mutate every human on Earth. However, the X-Men blocked his efforts to create an entire planet full of guinea pigs for his twisted experiments.

Sinister sometimes aids the X-Men, but only when it furthers his own ends. He helped the reformed thief called Gambit save the savage Sabretooth's life when the Adamantium metal was stripped from the mutant murder machine's skeleton, and assisted the ragin' Cajun once again when he became trapped in the 19th century. In almost every instance, however, Sinister exacts a price costly to the soul.