"Rhedosaurus"
The Beast From 20,000 Fathoms

Stats:
A gigantic prehistoric sea dinosaur.

Origin:
After an atomic bomb test in the northern polar ice cap, the gigantic dinosaur "Rhedosaurus" is awakened from his sleep. Then plots an undersea course for the Eastern US seaboard, and proceeds to wreak havoc on New York City.

Facts:
Best appreciated as a vintage showcase for the stop-motion animation of special-effects legend Ray Harryhausen. The film is based on the short story "The Fog Horn" by Ray Bradbury.

More Facts:
This film is often sighted as being the main inspiration for Godzilla.