It Came from Beneath the Sea

1950s American sci-fi horror. A nuclear submarine spots a giant mutant killer octopus in the Pacific Ocean and tries to destroy it.

The creature escapes and wreaks havoc along the West Coast before heading for San Francisco, where it destroys the Golden Gate Bridge and sparks a mass evacuation of the city.

Commander Peter Mathews (Kenneth Tobey) and marine biologist Dr John Carter (Donald Curtis) race to stop the monster's deadly rampage before it's too late.