9. The Alien Apocalypse
With slightly more variance than the zombie apocalypse, the ET kind usually features marauders from beyond the stars. They might be here for our water (Battle: Los Angeles), our family and friends (Invasion of the Body Snatchers), or just for the hell of it (Mars Attacks!), but one thing doesn't change: it's always bad news for homo sapiens. With their heat rays, death rays, and other advanced technology, they can subjugate us to their will pretty much at whim. Sometimes they're here for our good (The Day The Earth Stood Still) and sometimes they're cute and cuddly (E.T.), but, more often than not, they're here to wipe us out (War of the Worlds) or, at the very least, set up shop (The World's End). Alien apocalypse films tend to be about humanity uniting against a common threat, setting up acts of noble sacrifice from unexpected parties and inspiring speeches from more outwardly heroic figures (Bill Pullman's in Independence Day pretty much set the benchmark) - if zombies are all about the loss of identity, humanity being reduced to a homogenous mass (it's been used as a metaphor for both Communism and rampant capitalism), then alien invasions are about us asserting that identity, defending ourselves from The Other. We might not be able to take them on shot for shot, pound for pound, but their lack of resistance to our germs/yodeling/computer viruses will inevitably allow us to prevail. There a few, if any, post-alien apocalypse films, unlike with the next contender...