Warning: This article contains spoilers for X-Men '97 episode 10, "Tolerance is Extinction - Part 3."

Summary

• Mister Sinister was transformed into an aged husk in X-Men '97 episode 10, thanks to Jean Grey's huge power boost.
• Mister Sinister may have been stripped of all his abilities in X-Men '97's finale, leaving his future in the animated series uncertain.
• The fact that Mister Sinister didn't simply die suggests he may have retained some powers, creating the opportunity for his return.

Mister Sinister underwent a huge transformation in X-Men '97 episode 10, creating many questions about the legendary X-Men villain's MCU future. Continuing the story of X-Men: The Animated Series, which ran for five seasons between 1992 and 1997, Marvel Animation's X-Men '97 caught up with the X-Men roughly a year after Professor X's departure from Earth. The ten-part animated series, which concluded on May 15 with X-Men '97 episode 10, "Tolerance is Extinction - Part 3", pitted the X-Men against a variety of classic Marvel villains, including the Friends of Humanity, Mojo, Madelyne Pryor's Goblin Queen and human-Sentinel hybrid Bastion.

Iconic X-Men villain Mister Sinister also posed a significant threat to the titular team in X-Men '97, first making himself known in episode 3, "Fire Made Flesh," during which he activated the Goblin Queen inside Jean Grey's mysterious clone, Madelyne Pryor. Sinister also infected Scott Summers and Pryor's son, Nathan, with a techno-organic virus, forcing the X-Men to send him to the future, where he would eventually become Cable. Later on, Mister Sinister was revealed to be working alongside Bastion to enact Operation: Zero Tolerance, but this unexpected partnership would lead to his downfall in X-Men '97's dramatic three-part finale.

Why Mister Sinister Looks So Different When He's Defeated In X-Men '97

X-Men '97's final episode, "Tolerance is Extinction - Part 3," saw Bastion's Prime Sentinel plans revived after Professor X reversed Magneto's electromagnetic pulse from episode 8. This provided Bastion with even more strength, and reactivated the villain's army of Sentinel robots, which he used to capture Beast, Storm, Forge, and Morph following the Mister Sinister-controlled Cable's attack on Jean Grey in the previous episode. When preparing to execute Cable, however, Jean Grey emerged as the Phoenix once again, and she used her drastic new power boost to defeat Mister Sinister, transforming him into an aged husk of his former self.

Using her powers as the Phoenix, Jean Grey alters Mister Sinister's genetic code, burning away the mutant DNA that he had spliced into himself over the years. This seemingly reverts Mister Sinister, perhaps now simply Nathaniel Essex, to his true physical form of a withering old man. Nathaniel Essex was born in the mid-1850s, but his genetically-engineered mutant abilities gifted him incredible longevity. With these powers stripped away, Mister Sinister's long life caught up with him in X-Men '97 episode 10, leaving him deformed and weak, apparently defeated once-and-for-all, though the future for the iconic X-Men villain is left uncertain.

Has Mister Sinister Lost His Powers?

It stands to reason that Jean Grey's Phoenix would have taken all of Mister Sinister's abilities, leaving him powerless in the future of the animated series. However, if the villain had lost all his powers, surely he would have simply died on the spot, given that he's over 150 years old. Since this didn't happen in X-Men '97's finale, it seems the villain may have retained some of his abilities, perhaps giving him the opportunity to return, perhaps stronger, in X-Men '97 season 2 or 3, both of which have been confirmed to currently be in development at Marvel Animation.