"When I was reading comics when I was 15, Superman didn't deal with rape so much, you know? There weren't a lot of dark elements to mainstream superhero comics. I think that it's pretty obvious that one of the things that's hurting comics is that the subject matter is so inappropriate for a mass audience. You know, Marvel just did an intercompany crossover which was supposed to be something all of their readers can read, and it had guys ripping each other in half and intestines were flying all over the place. That's the kind of thing that you would see in a Walking Dead comic. I don't want to see Spider-Man swinging around, tripping in intestines going, 'Aw, crap! What a mess!' That's not the kind of thing that's going to get Billy down the street off of his Xbox. I think part of the problem is that the writers and artists that are doing these books want to write them for themselves, instead of for the audience they should be writing to. And I think that's a real problem. [...] I think it's cool to see superheroes rip people in half. Because if superheroes really had superpowers, that's the kind of shit that would happen, just on accident, you know? And so I created a book called Invincible that isn't meant for a younger audience, and has superheroes ripping each other in half. But I didn't try to take Superman and turn it into that book. I did my own book. I think that's the key."
-- writer Robert Kirkman, on the gradual darkening of mainstream superhero comics