Godzilla stomping back to theaters

[Rain Man]

Originally Posted by Amnorix

Ok, this is a crazy long shot, but I've seen crazier on here, so why not...

There was a movie on the creature double feature once -- it was about a scientist who somehow helped bring a creature that was from another planet or something to earth. He, of course, thought it would be a good idea. He helps protect the creature, which as best I can recall is living in a cave of some sort. It was about the size of a human, and my memory (very vague) wants to make it very roughly bat-like.

It turns out (surprise!) that the creature is evil in some way, and ultimately the idiot who brought him to earth has to kill it. My memory is that that guy and the creature fight it out and both die. Or something.

Based on that pathetic description, does anyone have any idea what movie this might be? It made an impression on my young mind, and every once in a while I wonder what the movie was. 35 or whatever years later, an inquiring mind wants to know.

Other than the ending, it sounds like a plot ripoff of My Fair Lady. Was he teaching the creature to function in high society?