Every comic book, cartoon and movie featuring the X-Men should in all fairness have a credit on it somewhere, "Inspired by the 1945 'Baldy' stories of Henry Kuttner and Catherine L. Moore."
I'd read some stories by Henry Kuttner that I thought were clever and amusing (the Hogbens series, the one about Gallagher the drunk inventor) and some that seemed tedious and lame (those uninspired Elak of Atlantis epics). But until I found myself lost in MUTANT, I didn't quite realize how astoundingly good Kuttner (and his wife Moore, usually collaborating to some degree, here as "Lewis Padgett") could be. This is the real stuff, genuine pulp style science fiction. It's full of inventive details and clever plot twists, with a strong premise that today seems to have a even stronger appeal for readers than it did back then..
Created by atomic radiation, a new race of bald telepaths fights a desperate secret war between their two factions of the sane and the paranoid mutants. The paranoids (who at one point are mockingly called "Homo Superior" as compared to Homo Sapiens) see themselves as godlike supermen inevitably destined to conquer and rule the pitiful normal humans. The sane mutants are struggling desperately to keep knowledge of even the existence of the paranoids from become known, fearing that vastly more numerous normals will massacre them all. It's not a simplistic struggle between pure good and evil, as even the sane Baldies resent being forced to submit and bow their heads, keeping a low profile in the hopes that their children will be fully assimilated.
(Did Stan Lee ever mention in the letters columns that he and Jack Kirby had enjoyed the 'Baldy' stories by Kuttner? Certainly, they both had read a lot of pulps back in the 1940s, Kirby even illustrating some of them. As Jewish men alive during the Holocaust, did the 'Baldy' stories have special resonance for them?)
All the mutants are born completely hairless, but in an attempt at blending in and going unnoticed, most of them wear fake eyebrows, eyelashes and wigs. At first, the more defiant and unruly mutants go around natural (I'm bald and I'm proud!), but widespread lynching dampens that trend. We as readers following the Baldies can see they are mostly honorable and discreet, would never use their telepathic abiities unfairly and in fact go out of their way to do useful constructive work in their careers. Still.... you can see how just knowing there are people out there who can literally read your mind without your knowledge or consent would be seen as threatening. And who doesn't have dirty little secrets and vices they want to keep hidden? (Put your hand down, you in the back. You're as bad as the rest of us.)
Although they can communicate freely with each other, the Baldies can only read a normal human's surface thoughts; it's a real effort to put a thought into a person's mind, and there's no sign that Baldies can mentally coerce anyone, let alone brainwash or control someone's actions. This makes them still dangerous but much more vulnerable and recognizable than Marvel mutants who can blast destructive rays from their eyes or make Army tanks fly apart. In addition to the tension of the desperate underground war going on unsuspected by the normal humans, the "Baldy" series also has an intriguing backstory that is gradually revealed.
[An incredibly lengthy review of the "Baldy" stories can be found over on my Retro-Scans site, for those who are interested. One more indication of how Lee and Kirby were deriving the X-Men from the "Baldies" is shown in how Magneto also had telepathic powers in the earliest issues. He was not as capable as Professor X, but he could scan minds and astral travel. This was quickly dropped, but it is an echo of Kuttner's vision of two groups of telepathic mutants warring with each other over humanity.)