User blog comment:LectrPazillo/Main Character's Death/@comment-4832338-20131126101809

Stan, Kyle and Cartman were actually killed by the nuclear explosion in Imaginationland, only to be resurrected by Butters, who survived the explosion without any explanations as to why. This, along with Kenny's semi-permanent death, reinforces the fact that on South Park it is rather easy to kill off a main character, only to bring them back without a logical explanation.

That being said, I don't know much about Family Guy, but on South Park killing off any of the major characters would devastate the fans enormously. Personally, I'd hate to see any of the major characters written off the show.