The 90's era of the X-Men led to increasing levels of popularity for Marvel's mutants as some of the best creators in comics came together to carry the team through a number of epic crossovers and status-quo changing events. The X-Men welcomed new members and milestones, though they also encountered a few new villains as well.
The new villains of the 90s had a sharper edge than some of the characters the X-Men had dealt with in previous eras, though some of them hit harder due to their personal connection to the team or other villains that had appeared over the years. Most of these characters have continued to play a large role as some of the X-Men's deadliest villains.
10 Fabian Cortez Was A Power Manipulator Who Usurped Magneto's Acolytes
Magneto gathered a team of mutant followers around him that included a mutant named Fabian Cortez, whose mutant ability to amplify and negate mutant powers and energy sources made him a useful tool in Magneto's powerful army. However, he manipulated Magneto in order to kill the weakened Master of Magnetism in secret and used a false story to usurp the Acolytes.
Cortez was responsible for the Bloodties crossover between the X-Men and the Avengers when he kidnapped the granddaughter of Magneto to make a statement in Genosha. He's died a couple of times over the years but has found a new role in the Krakoan society as a power enhancer working with S.W.O.R.D.
9 Gamesmaster And The Upstarts Played A Dangerous Game With Mutant Lives
A powerful omnipath known as Gamesmaster was the orchestrator of a deadly game held among rich, bored mutant socialites like Shinobi Shaw, Graydon Creed, and even Fabian Cortez. The team also introduced powerful new mutants like Sienna Blaze and the time-traveling Trevor Fitzroy before adding new members like the Fenris twins.
They all competed for points based on the status of the mutant heroes they managed to kill, with Gamesmaster occasionally sending them on organized hunts for young mutants like the survivors of the New Mutants and Hellions. The Upstarts disbanded after a few appearances and members like Graydon Creed and Trevor Fitzroy continued to impact the X-Men and their future.
8 Omega Red Is A Powerful Energy Vampire Who Carries A Deadly Death Spore Virus
While it was revealed that the character had an extensive history with other mutants like Wolverine and Banshee, the Russian serial killer known as Omega Red made his debut in the 90s. Arkady Rossovich was used in mutant experimentation that dramatically increased his threat level, transforming him into an energy vampire.
He used his powerful Carbonadium coils to ensnare and drain his enemies of their lifeforce, all the while exposing them to the deadly death spore virus that he had to release as it threatened to destroy him instead. Omega Red has remained one of the X-Men's most brutal villains whose abilities have nearly proven fatal to a number of the X-Men over the years.
7 Bastion And His Prime Sentinels Targeted The X-Men During Operation: Zero Tolerance
The X-Men have dealt with mutant-hunting robots known as Sentinels since some of their earliest comic moments, and they lived under the haunting fear of a future overtaken by the Sentinels that they encountered in the "Days of Future Past" storyline. That era's Sentinel was known as Nimrod, and it traveled back in time to threaten the X-Men a number of times over the years.
Nimrod and Master Mold were sent through the Siege Perilous together and reborn as a human/Sentinel hybrid known as Bastion, who organized Operation: Zero Tolerance. His goal was to wipe out the X-Men and launch an attack against mutantkind using his hybrid Prime Sentinels. Bastion returned a few times over the years with new and deadlier attempts to wipe out mutants.
6 The Phalanx Was A Techno-Organic Hive Mind Of Mutant Haters Like Cameron Hodge
Warlock was an alien member of the New Mutants who died during the X-Tinction Agenda event, though the transmode virus his kind used to transform organic material was taken and experimented on by a group of mutant-hating humans. They volunteered to use the virus to transform themselves into the techno-organic hivemind known as the Phalanx.
The Phalanx was a shape-changing being led by assimilated humans like Cameron Hodge and Stephen Lang who tried to kidnap the next generation of mutants in order to assimilate the mutant gene. The Phalanx on Earth were destroyed, though their hivemind was revealed to have been connected to another alien race of Phalanx that debuted in the 90s as well.
5 Emplate Was A Psychic Vampire Who Gained Limited Control Over His Victims
The next generation of mutants targeted by the Phalanx grouped together to form Generation X, where the young mutants in training encountered a few memorable villains during their time together. However, none of Generation X's villains are as memorable or impactful as the terrifying mutant known as Emplate.
The psychic vampire fed on the genetic material of others, though he was further deformed and traumatized after he attempted to conquer another dimension in a bid to claim enhanced power. Emplate is the older brother of Gen X member Monet St. Croix who currently helps mutantkind on Krakoa as part of the energy-draining system that keeps Krakoa fed and happy.
4 Stryfe Was Cable's Twisted Clone Who Formed The MLF And Created The Legacy Virus
The Mutant Liberation Front first appeared in the 90s as an enemy for the new mutant strike team, X-Force, that was formed by Cable. He was revealed to be Nathan Summers, the infant son of Cyclops who was raised in the future. However, he originally assumed himself to be the clone of Stryfe.
The MLF's leader was the mysterious but powerful Stryfe, a telepath and telekinetic who had been raised in the future by Apocalypse. He lived for years assuming he was the original Nathan Summers, though he learned the truth during the X-Cutioner's Song event. He also created the devastating Legacy Virus that fatally tore through the mutant community in the 90s.
3 Holocaust Was A Deadly Exile From The Age Of Apocalypse Who Lived Up To His Name
The collapse of the brutal Age of Apocalypse reality left a few exiles stranded in the mainstream Marvel universe, including the incredibly powerful and dangerous mutant known as Holocaust. Originally known as Nemesis, Holocaust was Apocalypse's son whose energy-absorption abilities led to the destruction of his body after he overdosed on lifeforce energy.
Holocaust wore a containment suit that allowed him to use his enhanced abilities to tear through his new reality. Holocaust brought Magneto's floating Avalon down to Earth and displayed his sheer power a number of times in battle with fellow AoA exile Nate Grey. Holocaust was killed in yet another alternate reality when his energy was drained by King Hyperion.
2 Onslaught Was A Deadly Psionic Being Created From Xavier And Magneto's Merger
The events of the Fatal Attraction storyline pushed Professor X to his limits, and he used his telepathic abilities to wipe the mind of Magneto. However, a part of Magneto's essence managed to infect Xavier's psyche, which led to the birth of a new psionic entity that would come to be known as Onslaught.
The malevolent entity took out the X-Men easily before it began adding additional power from mutants like Nate Grey and Franklin Richards to evolve past its physical form. The threat of Onslaught saw the Avengers and Fantastic Four sacrifice themselves to stop his increasing power, though he has returned a few times over the years.
1 Exodus Is A Powerful Omega-Level Mutant Who Followed In Magneto's Footsteps
Benett du Paris is the powerful omega-level mutant known as Exodus from the 12th century who first appeared in the 90s after he was freed from an icy prison by Magneto. The potentially immortal Exodus was one of Magneto's most loyal followers, and he took the reins of the Acolytes after Fabian Cortez was discovered for his treachery.
Exodus has a number of incredibly powerful telepathic and telekinetic abilities that make him one of the most powerful psionics in the Marvel universe who has been able to take on a combined team of X-Men and the Avengers all by himself. He currently sits on the Quiet Council of Krakoa as one of the rulers of the X-Men's new society.