14. Clover (Cloverfield)
A giant, rampaging quadrupedal behemoth equally as terrified by its own surroundings as those unfortunate enough to find themselves in its path, the leading monster of the Cloverfield franchise is not to be trifled with during its periods of uncertainty (or ever, really).
Having torn up the streets of New York City with reckless abandon, the creature bares similarities to a giant insect, with a fish-like face (with inflatable breathing pouches on either side) and a jaw with the ability of expanding well beyond what you'd expect. And while its size would make it a worthy opponent for the almighty Godzilla, the thing that makes it even deadlier are the smaller parasites it releases into the city that can kill unsuspecting people with a single bite.
Though not from outer space, later films have suggested that Clover (and his entire species) are interdimensional aliens, so that - and the similarities to other alien species - is enough to earn him a place on this list.