When you think about mutants stealing powers, you automatically think of Rogue. Her main power is, after all, power absorption. But she's not the only mutant who has stolen powers, sometimes from other mutants and other times from non-mutant heroes. Then, there are the times that powers are taken on a massive scale, to a point that entire communities are devastated. No matter the scale, losing one's powers can be devastating to a hero, whether they're a mutant or not. For others, it can feel like a blessing in disguise. Regardless, mutants stealing each other's powers is a classic move.
10 Becoming Mrs. Magneto
In the alternate reality known as Age of Apocalypse, Rogue and Magneto were something of an item, getting married and even having a kid together. But how is that possible since Rogue's powers mean she can't touch anyone, human, mutant or otherwise, without absorbing everything from them? In this reality, Rogue permanently absorbed a portion of Polaris's powers, another magnetic mutant. Rogue and Magneto came to the realization that their powers canceled each other out, allowing her to safely make contact with the Master of Magnetism and build a family with him.
9 Rogue Shuts Ms. Marvel Down
A prime example of a mutant stealing a non-mutant's powers is Rogue absorbing Carol Danvers' abilities. Rogue's ability to absorb powers is generally short term, meaning the effect wears off after a while. But the longer she maintains contact with someone, the longer the effects last.
Rogue's only actual mutant ability is power absorption. She took the abilities of flight, super strength, and invulnerability from the former Ms. Marvel, powers she has kept due to maintaining contact with Danvers for so long. Obviously, this worked out really well for Rogue. Unfortunately for Ms. Marvel, this put her in a coma for many years.
8 Mimic Becomes The X-Men
Mimic seems to make a lot of bad choices, particularly in how he tried to join the X-Men. His abilities let him absorb the powers of any nearby mutant but only for a short period of time. His stolen powers fade quite quickly as he moves away from his targets. But when in range of a variety of mutants at the same time, he can develop an impressive array of abilities. Mimic's first accidental meeting with the X-Men saw him hit on a pre-blue fur Beast's girlfriend which led to a confrontation between the two, which Iceman also got involved with. Mimic surprised the due by using their own powers against them before escaping.
7 Magneto Unintentionally Steals Wolverine's Healing Factor
Magneto tends to walk on both sides of the good and evil line, depending on what suits his needs at that time. This time he was on the wrong side of the line. As Magneto lounged on his space station, a group of X-Men made an assault on it in an attempt to thwart his plans.
Tired of their interference, he used his magnetic powers to forcibly drag all of the adamantium out of Wolverine's body. This left Logan in a devastated state, one he barely survived. The unintentional side effect of this act was burning out his healing factor, leaving the mutant without his signature power or his adamantium claws for quite some time.
6 A One-Woman Avenger Team
The era of the Uncanny Avengers was that of a team with more equitable treatment of mutant and non-mutant heroes. During that time, Rogue served as a member of the team. At one point, she borrowed the powers of all of the Avengers and X-Men present to fight the villain Exitar. This included not one but two Hulks, both Bruce Banner and Jennifer Walters. Even though it was a willing transfer and only a temporary one, Rogue achieved a level of power on that day she's rarely hit before, if ever, essentially becoming a one-woman team.
5 Hope Punks Out Cyclops
When you're an omega level mutant whose destiny could lead you to being either a messiah or a harbinger of death, you've got a lot of pressure on your shoulders to say the least. Hope Summers was raised by Cable at the behest of Cyclops, time jumping to avoid the attacks of Bishop who believed her to be evil. Eventually, Cable brought Hope back to the X-Men.
In a prelude to Avengers vs. X-Men, Hope and Cyclops had a huge argument. Unfortunately, Hope has the ability psychically duplicate the powers of any mutant near her. This allowed her to steal Scott's powers, hit him with essentially his own eye blasts and use a jet pack to fly away. That's how you win an argument.
4 Rogue Steals From Nightcrawler to Save Him
One of the most popular X-Men over the years has consistently been Nightcrawler. His demon-esque appearance combined with his teleportation abilities make him a unique member of the team. But it's his positive attitude and swashbuckling style that captured fan's affections. At one point, he was under the influence of the villain Proteus, who essentially has the ability to possess a person's body and use their powers, if that person has any. Rogue used her powers to absorb Nightcrawler's abilities and disrupt the villain's control over him. It was one of the rare times where she absorbed a teammate's powers without asking but the situation warranted it.
3 Vulcan Takes Out Adam Warlock
As one of the Summers brothers, Vulcan also has impressive mutant abilities. Vulcan is an Omega level mutant that can absorb and manipulate vast amounts of energy, including non-traditional, exotic sources. That includes Adam Warlock's impressive astral mystic powers.
In combat with Warlock, Vulcan was able to absorb, manipulate, and turn Adam's own abilities against him within seconds, robbing him of his powers. Adam Warlock has stood toe-to-toe with the likes of Thanos, highlighting how powerful Vulcan truly is.
2 Sinister Robs a Courier
Jacob Gavin, Jr., aka Courier, has the mutant power to control every molecule in his body. This gives him amazing abilities like shapeshifting and a shockingly robust healing factor. Courier's impressive mutant ability led Mister Sinister to take an interest in him. Sinister had tried more than once to forcibly collect a sample of Courier's DNA to work from but part of his ability lets him shut down said DNA from a long distance, leaving Sinister without a viable sample to work from. Eventually, Sinister was able to get what he needed from Courier and incorporated his abilities into his already formidable repertoire of powers.
1 No More Mutants
With three little words, the Scarlet Witch stole the powers of virtually every mutant on the planet, leaving many of them in an incredibly vulnerable and dangerous place. While the exact number is debatable, the estimated population of mutants around the world instantaneously dropped from roughly one million to a couple hundred. It was a cataclysmic event for what was supposed to be the next evolution of humanity. Scarlet Witch's curse lasted for a long time, with small pockets of mutants finding ways of regaining their powers. Using the Phoenix Force, Hope Summers was eventually able to return mutant powers on a large scale.