The family-friendly Spider-Man
Warning: contains spoilers for Savage Spider-Man #1!
Marvel's Spider-Man's most gruesome power is far too savage for the Marvel Cinematic Universe and will likely never be seen in a film. Peter Parker's powers are varied, with the ability to stick to walls and ceilings, the proportional strength of a spider, and a spider-sense that allows him to react to danger he can't even see. But in Savage Spider-Man #1, his most-used superpower - his webs - are repurposed in a horrifying new way.
Unlike the Sam Raimi Spider-Man films, Peter's webs are not an organic part of his powers that came with the spider-bite first depicted in Amazing Fantasy #15. The webs along with the concealed webshooters were created by Peter (in only a few panels, no less), and are a testament to his scientific knowledge. The webs are strong enough to support Peter as he swings through the air (and more judicious use of webbing can even support cars), but the strands dissolve after roughly an hour, meaning no unsightly webs are left behind after a battle.
In Nonstop Spider-Man, Peter Parker swings around New York City as he links a series of disappearances to a mind-altering drug called A-Plus, and the culprit is revealed to be Baron Zemo. A fight on Zemo's plane ends with Spider-Man being forcefully administered a tainted version of the drug, and as the plane is destroyed in the aftermath of the battle, Spider-Man finds himself hideously mutated into a multi-limbed spider-like beast, complete with mandibles and a very simplistic spider-sense taking over his entire thought process. Then the webs come in, and Peter's new horrific power is revealed.
Spider-Man, in his Savage form, now has the ability to shoot red webs from his mouth. These webs, once wrapped around a victim's head, allows Peter some form of control over his prey. Similar to the powers of Charles Xavier, he can read the memories of his victims - and control their movements. This notably horrifies even Zemo; as a character who makes no apologies for his Nazi past and even applauds the horrific actions of Germany during the second World War, to see Zemo mutter "God..." is a shocking sight indeed.
Spider-Man isn't yet a villain, but he's certainly no hero in the first issue of Savage Spider-Man. To see a usually-intelligent Peter Parker transform into a mindless creature is terrifying and somewhat tragic; Peter's intelligence is one of his superpowers, him being one of the geniuses of the Marvel Universe. Spider-Man fans can only guess what occurs next for the now-Savage Spider-Man.
