I was reading the (MUCH, MUCH BETTER THAN THE TITLE WOULD SUGGEST) comic Superman and Batman vs. Vampires and Werewolves. Ollie Queen, Mr. Green Arrow, appears in the book and casually mentions how he came back from the dead. I was an avid reader of Green Arrow at the time and I completely forgot his character went through the whole “died and come back to earth” thingy a few years back. That pretty much tells you all you need to know about how serious “killing off characters” really is.