Warning: The following contains spoilers for Non-Stop Spider-Man #5, on sale now from Marvel Comics.
Spider-Man is known for his many amazing powers, all gifts from being bitten by a radioactive spider years ago. At one point, however, these powers mutated him further into heavily resembling the arachnid that gave him his abilities. The iconic monster known as the Man-Spider is one of the unlucky web-slinger's most well-known forms, and the hideous beast returns once again in Non-Stop Spider-Man #5 (by Joe Kelly, Chris Bachalo, Cory Smith, Gerardo Sandoval, and others).
This issue explores the fallout of Peter Parker's alter ego being injected with a mysterious drug, and the result is the return of the Man-Spider. This could save him from the drug's effects, but it could also doom him even further. Here's the history behind the disgusting form and how it finally returned.
The Birth of the Man-Spider
The Man-Spider debuted in Marvel Fanfare #2 (by Chris Claremont and Michael Golden). In this story, Spider-Man and Angel had traveled to the prehistoric Savage Land where they were attacked by Brainchild, the leader of the mutates created by Magneto years prior. The villain used a genetic device on them which essentially devolved them, turning Angel into a gigantic bird-like monster and Spider-Man into the arachnoid Man-Spider. This creature was, as its name suggested, a humanoid spider with increasingly lowering human intelligence. Although Peter would soon regain his human form after using the device again himself, the villainous Plantman would later briefly turn him into Man-Spider again thanks to a special pollen.
A version of the Man-Spider showed up in the 90s Spider-Man animated series, where he resulted from Spider-Man's continued genetic devolution following the "Six Arms Saga." Later comics would also bring him back as a form that the villainess known as the Queen wanted to mate with. She sought to use their progeny to take over the world, with Spider-Man eventually going from Man-Spider to giant spider form after mutating further. Upon returning to human form, he found that his powers had been enhanced.
The Return of the Man-Spider
Man-Spider returns in the final pages of Non-Stop Spider-Man #5, which dealt with Spider-Man suffering from being injected with an experimental drug courtesy of Baron Zemo. The cocktail makes him lose much of his mind and faculties, with his intelligence and speech becoming noticeably affected. Zemo's ally Wulf betrays him, and Spider-Man takes advantage of the situation by escaping the Hydra aircraft with the villain.
Instead of being thankful for Spider-Man saving his life, Zemo attacks his confused and mentally distressed combatant. This causes the web-slinger to mutate and go on the attack, with his human form giving way to the almost completely arachnoid Man-Spider. Outside of Peter's hair billowing from the top of the beast's head, the form has almost completely removed all human aspects of his appearance, resulting in a truly terrifying monster.
This suggests that Spider-Man's psyche may be entirely gone, and that the mutation may be a result of his body attempting to compensate for the drugs. What this means for him or Zemo going forward is unknown, but it makes this version of the Man-Spider the most dangerous yet.