I have a couple of contenders but I'll start with:
I don't *need* a happy ending all the time (though I prefer them), but at least some resolution. Is there at least a manga that explains that happens afterword here?end episode spoiler wrote: Berserk.
The whole show ends, and we learn nothing about what happens afterword. NOOOOoo instead we get to see the main girl getting raped by hell demons, and the hero screaming in agony. Then for en epiloge, some old guy saying "don't get killed now".
Gaargh!
Ok, anyone else have an ending that's actually worse than this one? I'll consider myself warned.