20 Million Miles to Earth

The first U.S. spaceship to Venus crash-lands off the coast of Sicily on its return trip. A dangerous, lizard-like creature comes with it and quickly grows gigantic.
1957 also called The Beast From Space or The Giant Ymir
Directed by Nathan Juran, Staring William Hopper and Joan Taylor, The screenplay was written by Bob Williams and Christopher Knopf from an original treatment by Charlott Knight but this is really about Ray Harryhausen