What makes Spider-Man a good hero? The answer is a multi-faceted one, but can best be boiled down to Uncle Ben’s famous words of wisdom: "With great power, there must also come great responsibility." That’s why the physically and mentally superior Spider-Man can’t just go about offing bad guys - he’s honor-bound to use his amazing abilities responsibly.
So, why do so many images exist on the internet of Spidey committing horrific acts? The answer, as with comic books themselves, can get a bit complicated.
The concept of the Marvel Zombies series is rather simple - a classic zombie virus infects an alternate version of the Marvel Universe - but the results are gruesome. The bad behavior spreads as more and more super-powered people get transformed into the walking dead, including the Friendly Neighborhood Spider-Man.
In a scene too difficult for most to read, the zombified Peter Parker turns on his wife, Mary Jane, and his beloved Aunt May.
Spider-Man accidentally killed a KGB spy named Charlie during an adventure with Wolverine, and he didn’t take it very well. One issue of What If? Spider-Man Versus Wolverine, though, explores what might happen if he mishandled the situation entirely. This version of Spidey leans into his newfound lethality, as he cuts a bloody swath across Europe, killing those responsible for Charlie’s persecution - including terrorists and supervillains, like the Crimson Dynamo.
Few realize just how strong Spider-Man really is, as he's known for pulling his punches. At the very least, Spidey's strong enough to slap the gargantuan Wilson Fisk around like a rag doll in what must be considered one of the more embarrassing beatdowns in comics. This incident occurs when the Kingpin puts a hit on a recently unmasked Peter Parker - and Aunt May ends up taking a bullet.
In Spider-Man: Back in Black, an enraged Spidey shows up at the institution, letting Kingpin know he could easily end him if he ever decided to - if not for that whole “great responsibility” thing.
One of Spider-Man’s most impressive victories ever comes against Firelord, a Herald of Galactus. This clash comes during the period when Peter Parker is wearing the Symbiote suit, and he channels the alien’s power and rage to lay a serious whooping on a villain several weight classes above him.
Spidey beats Firelord so relentlessly that Captain America has to step in and pull the wall-crawler back - a dark and early portent of the violent potential of the Venom Symbiote.