My first choice for a "mythcomic" from the House of Entertaining Comics creates some problems. Though I didn't say so when I began this series, it's generally been my intention not to count anything that was a direct adaptation of a story published in another medium. For instance, I consider Robert E. Howard's short Conan story "The Tower of the Elephant" to be one of the great myth-stories of popular fiction. But I would never cite the Thomas-Smith adaptation of the story, published in Marvel's CONAN THE BARBARIAN #4. It's arguable that Thomas and Smith may have added their own mythopeic elements to the mix, but nevertheless, the source of the mythic structure is a prose story, not a comics-story.
Similarly, I would never include any of EC's famous adaptations of Ray Bradbury's work. Yet what about "swipes?" As this Wikipedia entry makes abundantly clear, publisher William Gaines had the habit of delving through published SF-stories and "lifting" ideas, which were then redone as "new" stories by raconteurs like Al Feldstein. The story goes that Gaines lifted one of Bradbury's stories, and that Bradbury wrote him, politely asking for payment for said adaptation-- a bit of indirect dickering that led to several fully approved Bradbury adaptations by E.C.
Yet a swipe doesn't have to be an exact reproduction of the original story. I have not to my recollection read the 1936 Henry Haase prose tale "He Who Shrank," but this blog-summation of the story suggests to me that writer Feldstein and artist Kurtzman only swiped the basic idea of a protagonist who is (a) exposed to a element that causes him to shrink endlessly, and (b) because of this, finds himself plummeting through a host of recursive micro-universes.
The dominant Campbellian function evoked here is the *cosmological,* in that Feldstein's protagonist Karl is constantly witness to all the wonders of the microscopic world, seen for the first time on an equal footing. I can't prove it, but when he shrinks into the "sweat ducts" of his mentor and learns that the older man has tuberculosis, that sounds a bit more like Kurtzman's wry sense of humor than Feldstein's-- though for all I know it might appear in the Haase story.
In addition, the story is particularly accomplished in the psychological arena, in that Karl is constantly shifting from being a godlike giant, able to cause havoc to lesser beings with no more than a sneeze, to dwindling into relative nothingness-- which is perhaps a little further than even Jonathan Swift went with the basic "relative size" trope.
Interestingly, the story's conclusion holds out some meager hope that someday Karl may shrink into some super-advanced cosmos where he can be cured of his affliction-- though the dominant effect of the story is to remind the story's interlocutor (who listens to Karl's story) that even Earth's advancements may pale before "what exists in the infinite cosmos."