Alien Trespass.

In 1957 a fiery object crashes into a mountaintop in the California desert, bringing the threat of disaster to Earth. Out of the flying saucer escapes a murderous creature, the Ghota, bent on destroying all life forms on the planet. A benevolent alien from the spaceship, Urp, inhabits the body of Ted Lewis, an astronomer and with the help of Tammy, a diner waitress, sets out to save mankind.