X-Men (1963) #8
First appearance of Unus, the Untouchable. "The Uncanny Threat of Unus, the Untouchable!" is written by Stan Lee with art by Jack Kirby and Chic Stone. This issue also features the premiere of Iceman's new smooth, icy look (no more jolly snowman). As the newly appointed field leader of the X-Men, Scott (Cyclops) Summers pushes his fellow mutants to their limits in rigorous battle training. And while they can't quite understand why their teammate is being so strict at the time, a quick trip into New York for some rest and relaxation shows why the X-Men must always be on their guard. Feared and hated by normal humans, the X-Men must always try to keep their identities secret. But when Hank (the Beast) McCoy sees a young boy in peril, he sheds all pretense of normalcy to save him. The gathered crowd thanks him with anger, fear and prejudice.
As Professor Xavier plums the depths of a near-bottomless cave in search of his old foe Lucifer, Cyclops faces his first crisis of leadership on his own. Disgusted by the attitudes of some normal humans, the Beast calls it quits. Seeking a new life outside the X-Men as a professional wrestler, Hank's first opponent is a powerfully built bruiser called Unus. But despite his great strength and agility, Hank finds he can't come close to even touching his opponent as an invisible wall of force repels all of Unus' attackers. The untouchable mutant is quickly approached by Mastermind of Magneto's Brotherhood of Evil Mutants to join up. But Unus chooses to pursue a lone career of crime. That choice puts him on a collision course with the X-Men, who go into battle for the first time without the bouncing Beast at their side. But why does it appear that Hank is actually helping Unus by constructing a device to magnify his incredible power?