Films: Chosen Survivors (1974)
Height/Weight: That of average vampire bats.
Summary: There they go again, those crazies going on about how we're all gonna have to go underground to escape the incoming nuclear war. Has anyone actually considered that there is NO vacancy down there? Not with these little buggers around, certainly.
History: A bunch of randomly chosen folk have been drugged and placed into an underground facility to wait out the aftermath of a nuclear apocalypse. Seems alright, end of the world notwithstanding...until you consider the swathes of vampire bats that happened to be living there in the first place.
Notable Kills: Nothing special.
Final Fate: Eventually, the nuclear story is revealed to be a hoax, and the whole thing was one big experiment. Of course, the bats weren’t part of the plan, and the surviving folk are carted out as the bats overtake the facility.
Weakness: Anything conventional.
Scariness Factor: 3-One bat in a cramped space is a nuisance. Now imagine the full force of a bat flock coming at you. Sure, they're adorable, but those fangs are there for a reason.
Trivia: -The vampire bat isn't nearly as vicious as this movie would make you think. Native to South America, these bats tend to stay away from humans, and prefer the blood of livestock. With that said, they can bite humans given the circumstances, and can accidentally spread diseases with their bites, like rabies.
-Bat swarms can get utterly enormous, almost as large as bird flocks can. One swarm was recorded with more than 40 million bats in it.