mm you mentioned Night Of The Lving Dead, that has a well bleak ending! The hero gets mistaken for a zombie and shot, and zombies take over the world! I think the one you mean is Evil Dead 3, which is more comedy than horror. I haven't seen 28 days later. But pure horror films, I think they pretty much do always have bleak endings where the bad guy wins... even if it's just to leave room for endless sequels!