I find the *doppelganger-*style aliens from Invasion of the Body Snatchers, The Thing, etc. to have the most disturbingly practical and efficient invasion strategy. While other alien conquerors must rely on overwhelming force to defeat a native population, the Body Snatchers don’t need to be any stronger, or faster, or even smarter than their victims. Dangerous microbes in the environment? Not a problem for these guys; while other, less subtle extraterrestrial invaders might experience humiliating setbacks from terrestrial microfauna, the Body Snatchers gain all the necessary resistance from the domestically evolved forms they mimic. They simply drop in on a pre-existing ecological niche and make themselves at home, causing minimal disruption of the target ecosystem.
And most importantly, they win. With alarming frequency, they achieve victory or at least an opportunity to strike again. Ask Dr. Binnell from the original Body Snatchers; he’ll tell you a few things. And what about that non-ending for Carpenter’s The Thing? Even when they’re not victorious, the Body Snatchers and their ilk have the uncanny ability to turn defeat into uncertainty, and thereby end their movies with a big question mark. “The End…or is it?” You never see a lone Martian war machine sneaking off over the horizon at the end of any version of War of the Worlds, do you? Of course not! It’s the Body Snatchers, I tell you! Binnell knows! Macready knows! You’re nex