9. The Mist (2007)
There is going to be some debate on this one because some would classify The Mist as a horror movie, but since this has creatures from another dimension, this can easily be classified as science fiction. Either way, it's incredibly depressing. After a large storm, a group of people in Bridgton, Maine are in a grocery store when a mysterious mist descends on the city, inside which are vicious creatures ready to kill anyone who strays within. The townspeople try to fight off the monsters for as long as they can, and the film trades openly on the traditionalist expectations that lots of expendable people will be killed off, before a select group are able to overcome the odds and escape. Sadly, it's a little bleaker than that. While this sounds like standard monster survival movie fare, what separates the Mist is the desperation that the heroes feel: they fight as much as they can, but how do you fight something you can't see? It is as if the characters seemed resigned to their fate once the mist sets in, and while the ending is too good and affecting to be expressly spoiled, it is one of the bleakest of any film endings ever.