10 Superheroes Who Broke Their Own Rules
2. Spider-Man Kills Morlun
"With great power comes great responsibility" has become a defining line in pop culture. Even people who have never read Spider-man know that line. Spider-man, meanwhile, has forggoten the responsibility aspect of that when it comes to collateral damage on numerous occasions, resulting in the deaths of a few villains.
The argument can be made that Green Goblin's death at the hands of his own glider was partially Spider-Man leaping out of the way of the Goblin Glider. How about Whisper, a villain Spidey uses as a human shield against a different blast that killed him?
Again, that's not technically him actively killing the person but more acting in an automatic self-defense response. There's also Charlie, a woman that Peter literally punches in the face and dies, but that too was an automatic response since he thought he was fighting Wolverine, who could easily have shrugged off the super-strength punch.
The two direct times that Spider-man has killed someone has been The Finisher, a Red Skull assassin who Spider-man blew up with his own missile. It counts as directly killing him because he sent the first missile safely into the water, so the second one could have also gone there but he launched it back at The Finisher's tank instead.
The other, from Spider-Man: The Other, is Morlun, a villain that Spider-Man, a half-spider at the time, EATS! HE EATS A DUDE! With great power, comes even greater accidents it seems.