When Mimic made his first appearance in 1966’s “X-Men” #19 (artist Werner Roth and written by Stan Lee), Calvin Rankin was caught in a chemical accident by his father which gave him the ability to take on the knowledge and skills of anyone he wanted. When it came to the X-Men, Mimic discovered he could absorb the Beast’s athletic ability, Cyclops’ power beams, the freezing powers of Iceman and Marvel Girl’s telekinesis, but Professor X erased his memory.
In 1966’s “X-Men” #27 (Roy Thomas, Werner Roth), Mimic was caught in a blast that revived his memory, and he demanded to be allowed to join the X-Men. With his combination of all their powers, along with Professor X’s mental abilities, the X-Men seemed helpless in front of him. It turned out the X-Men were just pretending and went on to beat him, but Mimic came back to become an enemy and an ally many times, and even joined Norman Osborn’s Dark X-Men team. He could copy their powers, but not their honor.
He’s a beloved antihero now, but the “merc with a mouth” started out as a supervillain in “The New Mutants” #98, created by Rob Liefeld and Fabian Nicieza in 1991. Deadpool was a sarcastic killer-for-hire who fought for different supervillains like the Kingpin, and sliced his way through the New Mutants and later X-Force. Over time, he evolved into a genuine hero who got his own miniseries. He loves guns and swords and little pouches, and people keep letting him onto their teams for some reason.
In 2004’s “Cable & Deadpool” #8 (Fabian, Nicieza, Patrick Zercher), Deadpool is actually hired by the X-Men to stop Cable, who’s launched a floating fortress in a desperate plan to “save the world.” The X-Men reluctantly agreed to bring Deadpool onto the team, even though he demanded to wear Jean Grey’s uniform. Deadpool ended up moving on from there, but the X-Men never forgot him, especially how he looked in a thong.