The morality of superheroes killing is a recurring idea in Brian Michael Bendis’s Avengers books. Usually, it is raised as an option and shown to be a faulty one. When Clint Barton ignores Spider-Man incredibly whining, childish arguments against killing Norman Osborn (they basically amount to the lame “But it’s wrong! ALWAYS! SO THERE!”), he’s captured by Osborn and shown the error of his ways. Any time the idea of killing is actually discussed and put into action, it is shown to be faulty. Yet, subtle killing happens quite often.
In Age of Ultron #10, Hank Pym and the Avengers kill Ultron. They execute him while laying a savage beating on him. There is no question about if it is the right thing to do or not. Killing Ultron, a sentient lifeform, is the complete and total right thing to do. It is the just and heroic thing to do. And no one questions that. No one questions killing Ultron. Just as no one questioned killing the Skrulls in Secret Invasion. They question killing everyone else. Just not robots and aliens. There’s not even a hint of debate over the concept, it’s simply taken for granted that, while the Avengers don’t kill, that only applies to humans. Aliens and robots, despite being sentient, living beings that should, theoretically, have the same rights and considerations as any human, are Lesser Than. They are slaughtered without a second thought or a moment of hesitation. Norman Osborn is a crazy man whose rise to power ultimately led to him starting a war with Asgard and unleashing a mentally unstable being of near unlimited power. But, of course, killing him would have been wrong because real heroes don’t solve problems with killing.
Hank Pym invented Ultron, so Logan decided to kill him before he could. This was seen as wrong (and the story revealed the action to be wrong for a variety of reasons, none having to do with actual morality). If you want to know how horrible a person Hank Pym is, think about the fact that simply telling him about Ultron and what happens when he invents the robot isn’t enough to stop him from doing it. It’s a challenge to Pym at that point. He is a fucked up, reprehensible person who is hard to classify as a hero at that point. No, really, what kind of person learns that they invent a machine that gains sentience and dedicates itself to killing every human and decides to go ahead and invent it anyway? A terrible, awful person. It’s easy to relate to Wolverine’s first instinct regarding Pym... Yet, the story reveals that Pym is not the one that needs to die; only Ultron.
(By the way, here’s something that never came up, but I’m almost surprised it didn’t: when Logan and Susan Richards return to the present, Logan doesn’t go after Pym. Part of me could definitely see a take on Logan that would involve him deciding that Pym was such a terrible person that, while he won’t kill him, he will fuck him up a bit because he would always invent Ultron no matter what. I want to see that story involving the duplicate Logan from Age of Ultron. He shows up, growls “Remember me?” and Hank Pym wets himself. Good fun for all.)
The only character that seems to recognise what actually happens is Hank Pym as he does what is necessary: kill his child. He is not happy to do this. He watches in what seems to be horror as Ultron is killed. When it’s done, he sits with his head in his hands, depressed and saddened that it has come to this. That is the reaction you would expect from a hero when he is forced to kill a villain. And it is for a robot that we’ve seen, unchecked, would do its best to kill every single person on the planet. There is nothing heroic about mourning its death. Pym’s sadness is not heroic, it’s another example of just how misguided he is. The Avengers are right to kill Ultron and right not to question the morality of it, because it is so obviously the right thing to do. It is the necessary thing to do. What I find sad is that this sort of thinking is reserved only for robots and aliens.