11 Most Terrifying Sci-Fi Movie Monsters

Who says dumb B-movie sci-fi still can't be scary? Tobe Hooper's 1985 sci-fi horror opus might feature some of the single most absurd monsters from beyond the stars ever put to celluloid, but that doesn't make them or what they can do any less frightening.

Essentially vampires, these shape-shifting aliens reside inside a massive (150 miles in length) crystaline spacecraft hidden in the tail of Hailey's Comet, going from planet-to-planet and sucking their populations of their lifeforce and leaving their civilizations in ruins. They appear as the most attractive and enticing members of their victim's species, catching them off-guard or entrancing them with their unearthly beauty.

Their victims don't just die though, they become shambling, husk-like ghouls who themselves feed off of others' lifeforces and in turn turn them into ghouls. What's more, the space vampires probe the minds of their victims to manipulate them into doing their bidding without them realizing it, and can even posses the bodies of their unknowing victims to move around undetected.

In the span of only a few hours, they've reduced London to an apocalyptic wasteland, and return unabated to their spacecraft to return again in another 75 years.