The X-Men remain one of the most unique superhero teams in the Marvel Universe. Unlike The Avengers and Fantastic Four, the X-Men are feared and hated by most of the general public due to the simple fact they are mutants. It is this prejudice and hatred that has moved them into the role of one of the most important teams in comic book history.
While their awkward relationship with the public remains one of the most interesting things about the team, they also deal with some of the most horrifying villains in the world. These villains include those who hate them because they are mutants to evil mutants who make it hard for anyone to ever accept the X-Men for who they are. Here is a look at the 10 most evil villains the X-Men have ever faced.
10 THE HELLFIRE CLUB
While they have lessened in importance throughout the years, there was a time that the Hellfire Club was responsible for one of the worst moments in Marvel Universe history. It was the Hellfire Club that kidnapped Jean Grey and then messed with her mind enough to unlock memories of her past that Professor X had locked away.
This sin, in turn, led to the Phoenix Force to taking control of Jean and unleashing the Dark Phoenix, a being that destroyed an entire universe, killing billions in one moment. Unleashing the Dark Phoenix on the world and destroying a young girl's life cements their spot as some of the evilest villains the X-Men have ever faced.
9 APOCALYPSE
Apocalypse is one of the first mutants in history, although it took a couple of decades before he made his first appearance as an X-Men villain. En Sabah Nur has lifetimes of experience and knowledge, and that makes him more dangerous than any other evil X-Men villain.
Apocalypse is immortal, can alter his size, regenerates from any injury, and can even use advanced technology to give himself other mutant powers. That makes him one of the most overpowered mutants in history. Add in the fact that he turned nice guy Angel into an assassin, and it ups his evil factor infinitely.
8 MAGNETO (ULTIMATE UNIVERSE)
Magneto almost doesn't deserve to be on this list as he may be evil, but his heart is in the right place as far as his goals and desires. He was born in and lived through the Holocaust and saw the evil that lives in human's hearts. He doesn't want mutants to be the next to fall.
However, move over to the Ultimate Universe, and his actions blow away anything Magneto considered in the 616. In the Ultimate Marvel Universe. Magneto committed an attempted genocide of his own, killing Charles Xavier as well as thousands of people including over 25 heroes and villains in Ultimatum.
7 ONSLAUGHT
Onslaught is the embodiment of evil as it is a mixture of Professor Xavier and Magneto. This creature came to life when Xavier shut down Magneto's mind in a rage after the Master of Magnetism almost killed Wolverine. While doing this, Magneto was also in a rage, and his negative feelings entered Xavier's mind, and Onslaught came into existence.
Onslaught then did the impossible. It destroyed the world. Onslaught was so powerful that the Avengers, Fantastic Four and X-Men couldn't stop him until they teamed up and then they all died in the battle. Franklin Richards created a parallel universe to save everyone, but Onslaught is one of the few creatures actually to succeed in ending the world.
6 SHADOW KING
While the Shadow King is not a mutant, he is one of the most dangerous villains the X-Men have ever faced. He is an evil being that has been around possible forever and enters the world while in possession of others. Many times, he chooses mutants as hosts.
Most fans got to know Shadow King as the puppet master in Legion and taking control of someone with the mental problems of David Haller is truly evil. He manipulates his victims by preying on the darkness in their minds.
5 MR. SINISTER
Mister Sinister is evil because of what he does to mutants, all in the name of science. He is Nathaniel Essex, a biologist who became obsessed with Charles Darwin's theories. However, he didn't possess the moral compass to stop him from experimenting on anyone and everyone he could get his hands on.
Mister Sinister began to experiment on people, including mutants, to try to help humanity reach its full potential, but his experiments were darker than anyone could imagine. He even created the clone of Jean Grey in Madelyne Pryor just because he wanted to see what powers their child would possess.
4 CASSANDRA NOVA
Cassandra Nova was a parasite born on the astral plane who tried to take control of Charles Xavier in the womb but failed in her efforts. However, the event allowed her to gain the power to eventually create her own body and become one of X-Men's most evil villains.
She has Xavier's psychic powers and can also shapeshift into other people, use astral projection, and control people's minds. What makes Cassandra more evil than almost any other X-Men villain? She is who ordered the strike on Genosha, which killed millions of mutants living there peacefully.
3 THE SENTINELS
Can Sentinels be genuinely evil? On their own, they can't be evil because they are just robots created by humans. However, when looking into the origins of the Sentinels and the humans behind them, they are pure evil, designed only to hunt down mutants.
There isn't a more significant threat to the mutants than the fear of humans. This fact is especially true when those humans have a lot of money and technology in their hands, or they have the government on their side. The Sentinels became a weapon of hatred and the personification of genocide, whether anyone wants to admit it or not.
2 BASTION
If the Sentinels, by the definition of their creation, are evil then Bastion might be the personification of evil. See, Bastion is the evolution of the Sentinels -- an android created with the sole purpose of wiping out the entire mutant race. The reason for its creation was the entire Onslaught incident.
The U.S. Government created the Operation: Zero Tolerance strike force and created Bastion, giving it control over the Sentinels. It could also create Prime Sentinels from humans. Add in the fact that he is almost unbeatable and has an insatiable hatred of mutants, and there might not be a more dangerous X-Men villain.
1 STRYFE
Mister Sinister created Madelyn Pryor to see what the child of her union with Scott Summers would look like. That child was Cable. However, Nathan Summers was hidden for his protection when Apocalypse started searching for him, and a clone was created.
That clone was Stryfe, who Apocalypse found. However, when Apocalypse discovered he was a clone, he discarded him. Stryfe was angered that his perceived parents and Apocalypse both abandoned him and he set out to destroy Cable. This hatred caused Stryfe to seek destruction by any means necessary.