It, the one that came form outer space

First appearance: It Came from Outer Space (1953)

Some weird-looking space monsters accidentally crash on Earth. The commit identity theft on some of the locals, because they know that earth people would attack and kill them because they are weird-looking, in order to repair their space-ship. The locals don't take kindly to the identity theft and attempt to attack and kill the aliens. So the aliens threaten to blow up the planet.
It's kind of like a cross between The Brain from Planet Arous and The Day the Earth Stood Still. Just not as Bizarre as the former and not as preachy as the later.

This movie was originally in 3-D!