15 Most Terrifying Movie Aliens Of All Time

15. Monsters

Gareth Edwards' 2010 horror was more about the thought-provoking commentary and intriguing character relationships than it was about its science fiction premise, but it simply couldn't have worked without the titular creatures showing up to work their magic every now and again.

Taking the term 'alien' to a whole new level, we know virtually nothing about this oddly majestic species of, well, whatever it is that they are. And being the artistic film that it was, Monsters wasn't afraid to highlight the beauty of these creatures - something that is showcased in the film's strangely moving mating scene.

That being said, the sight of giant squids with massive luminous heads that glow in the dark and more tentacles than a real squid could dream of isn't exactly the most endearing thing now, is it? No, chances are that if you saw one of these creatures floating through the air, you'd run the other way in horror - no matter how ethereal their mating session looked.