I knew the Xenomorph was going to take the cake - its a flawless monster. It also ranks #1 as the most plausible depiction of an alien in Hollywood by TREY The Explainer. :P

I think i would have added the cockroach from Mimic and MIB, and the Pale Man from Pan's Labyrinth - creepy AF!

Also, the gremlin on the plane was my childhood nightmare.