The other thing about comics is that, really, there's just the one specific version of the superheroes.  There's the one timeline where all of the stories written from the beginning of time until now are basically the definitive version of the characters and what really happens to them.  Yeah, there are "Elseworld" stories or "What If" stories that are designed to tell stories about what could happen if things were different.  In one story, like Kingdom Come, it pretty much showed what would happen if Joker had killed Lois Lane.  These stories are entertaining but they aren't the "REAL timeline".  I can find a thousand stories where Batman died instead of his parents or Superman killed but the definitive timeline is the one I go by.  Cartoons, video games, movies, and some of the comics go their own route with their own history but (Up until the "New 52"), everything that happened in the main line of comics is what happened.

In the main line of comics, Superman killed Zod.  It bothered him so badly that he exiled himself from Earth and now, he does everything he can to never kill again.  I'm not looking at the definitive stories or anything subjective.  This is the Superman that DC Comics (why do we call it DC Comics when "DC" stands for Detective Comics!?) has presented to us as the Superman.

Also *spoiler* Batman killed Harvey Dent/Two-Face at the end of Dark Knight returns.

And that Superman that has killed still has his morals.  He's still called the "Big Blue Boyscout".  Check out the cartoon called Superman vs. The Elite.  It's based on a actual comic book story from the real timeline where Superman takes on some heroes that aren't afraid to kill.  It's a response to people becoming fans of comic book heroes that kill without prejudice.  Superman will kill when he has no other choice but he's not like Wolverine or somebody that kills relentlessly. 

Is not the best movie, but for me is only behind batman, It lacks drama and emotional scenes, but the action scenes are better than all of the action scenes in the marvel movies incluying the boring action of avengers (only spiderman set pieces looks creative), a lot of people dislike the last fight in metropolis because it doesnt make sense with the superman character. But it was impressive! and I am glad than they showed that

I'm going to watch it for the first time tonight with my family. I hear it is really good.

Loved MoS. I enjoyed it for what it is, a comic-book movie. Plot holes are going to exist in every movie, especially with the way people nit-pick movies to death nowadays. It's a 2-hour movie. They can't possibly explain every little detail. Movies are meant to be an escape from reality. Some things you're just going to have to accept or use your imagination. You cannot possibly expect everything in the movie to make sense or be 100% logical. You would not be able to even claim that for the very source material from which the movie was adapted from. Many people would agree that the first two Christopher Reeves Superman movies were great. I concur, but if we were to all watch those again with the same critical lenses that we use today to watch movies, I guarantee that you can pick those 2 movies apart with things that make no sense and also fine a multitude of obvious plot holes.

Understand what I mean when I say definitive. Its not just about what DC says is the official timeline or what is canon. When I say definitive I'm talking about the generally accepted interpretation of a character. The reason why Superman killing Zod is even being considered an issue is because the general consensus even outside of die hard fans is that Superman doesn't do that. Comic books are constantly making one thing canon, then changing it, then going back, etc. Usually, if you want to really figure out what should be definitive you have to stick to a specific writer. For all the convoluted mess the X-men series has become, many die hard fans only consider Chris Claremonts run as definitive regardless of what Marvel says. With batman I actually consider Paul Dini and Bruce Timms animated series to be the definitive take on the character. I'm not just talking story lines (plenty of great ones from the comics), I'm talking about the actual character, what he believes in, how he reacts to situations, etc...

I'm not arguing that they can never do a superman kills moment, but they really blew their load with this one. The moment just falls flat when it could have been such a powerful moment if they had just established the character a bit more. It needs to be an established thing that SUPERMAN DOES NOT KILL! Then when he is forced to kill, it is a huge, powerful, shocking moment not the weak garbage that it turned out to be.

Honestly The Dark Knight Returns should never even be brought up when discussing definitive batman books. Its a great story but it is NOT Batman. Its just a quirky little elseworld tale from Frank Miller twisted mind. I don't know why people talk about it as though it defined the character... it changed the tone of batman in the publics consciousness but it did not redefine or define the character at all.

I'm also glad you brought up Superman vs The Elite. Its a perfect example of splendid writing where Superman saves the day WITHOUT KILLING ANYONE!

My bad. I said The Dark Knight Returns but I meant The Dark Knight (movie).  Batman kills at the end of that movie to save even less people than Superman did.  That's how the Joker won.  He made Batman kill and he made Gordon a liar and Harvey Dent corrupt.

But yeah, when superman killed in Man of Steel, I basically said, "What the fuck?" It came out of nowhwhere.  Hopefully, they explore that in the sequel.

Even if you forget how Superman was represented, as a movie in itself, it is bad.