10 Great Sci-Fi Movie Villains Who Only Appeared Once

We may be jumping the gun on this one, as there’s a chance that 2017’s uber-bleak space-set sci-fi horror Life might still get itself a sequel. It would be no easy feat, however, since the film’s ending implies that our entire planet is set to be killed off easily by this mutating monster. Pretty impressive for someone named Calvin, right?

Beginning his onscreen life as a mere blob of translucent veins and jelly, Calvin rapidly grows into a force formidable enough to off presumed leading man Ryan Reynolds a half hour into this intense thriller, and firing the now-adolescent slimeball out of the airlock soon proves no deterrent for his evil antics.

By the end of his evolution (that we know of—gulp), Calvin is a sizeable but still strangely see-through set of tentacles, flippers, and so many teeth, capable of slithering into smaller spaces than his obvious inspiration, the bulkier xenomorph of Alien fame. Still smaller than our human heroes, this gruesome creature makes up for his small stature with ferocity and terrifying ingenuity. Far smarter than most alien invaders, Calvin proves himself able to outsmart even our heroes, cementing his status as an unbeatable villain and leaving us wishing we could have seen more of the cretin.