20 Most Terrifying Enemies In Video Game History

19. SA-X - Metroid Fusion

The SA-X is the result of a parasitic infection which takes hold of Samus's power suit with the intention of transforming itself into a perfect copy, which is a scary enough idea in itself when you consider the firepower it'll gain. Never mind that Samus herself is especially vulnerable to the creature's attacks after a vaccination cripples her resistance to the SA-X's Ice Beam.

You're told early on that stealth and evasion are preferable to combat as engaging the SA-X armed with nothing but bravado and a death wish probably isn't the brightest idea. Hearing that the SA-X is dangerous is certainly not the same as experiencing it first-hand however, and the build-up to the big bad's sudden reveal is as spine-chilling now as it was over a decade ago.

You'll come to dread the sound of its footsteps with every fiber of your being, and the sense of overwhelming paranoia that it triggers is so pervasive that it's impossible to shake the feeling it'll enter the room at any second.