Common antonyms to "happy ending"?

I know you may specify to something like tragic, open end to describe actually what the end is like.

But do English critics/reviewer in movie magazines use a common term for movies with bad/evil endings or simply refer to them as no happy ending (as most movies have to have a happy ending) to classify such films? I mainly ask as I need some proper keywords to find those rare films.

There are some good answers here, but nothing quite on the nose, so I'll make my own humble contribution:

Does it at least have a happy ending?

Nope...it's pretty much a downer ending.

This is obviously much less formal than these other answers, but it's what I would use in normal American English speech.

You may say that a film or book has a tragic ending, and is therefore a tragedy.

The reason it's relatively common to say a movie has a "happy ending" is because movies are often specifically designed to be like that. A large percentage of the audience want and expect things to end on a positive note, just as when we were children we liked our bedtime stories to end with "and they lived happily ever after".

The two main problems with looking for an "antonym" are, firstly, that there aren't so many cases where it could be applied. Secondly, alternative ending types may be quite varied, so there's no generally applicable term.

Endings can be tragic, inconclusive, disturbing, etc., but in general these terms would apply to the whole movie, not just the ending. Sometimes the ending is described as a cliff-hanger (perhaps the director plans a follow-up movie, and wants the audience to be curious about how things are going to be resolved).

(Is this too obvious?) How about "unhappy ending"?