8. The Viral Apocalypse
What did for the Martians can do for us too. More generalized than the zombie virus but arguably more deadly, this bad boy - be it the black death or the common cold - can go airborne and there's more or less no way to fight it. Unlike with the zombie threat, you can't just cave its head in and by the time the eggheads are able to synthesize a vaccine it's almost always too late. Of all the triggers for an end of days, the viral apocalypse is often used as a generic set up for a post apocalypse: by the time the events of the film take place, the infection is over but the effects remain (Twelve Monkeys). The virus can take many forms, manifest in many way: it can kill you (Contagion), turn you into a vampire or mutant (I Am Legend/The Last Man on Earth), or you can just flat out go nuts (The Crazies). The virus kills indiscriminately, maybe with a few exceptions, and there's nothing you can do. You can't run, you can't hide. Like nature itself, this one is implacable. More often than not it's something we've cooked up in a lab that is set loose to wreak terrible destruction on mankind for its hubris, sometimes it comes from outer space (The Andromeda Strain). In any case, viral apocalypse movies tend to comment on the fragility of civilization, of the human condition - that for all our advancements, we can still be wiped out by a microbe.