Octaman (1971)

A scientific expedition to a remote fishing village discovers high levels of radiation as well as a strange mutant-like small octopus that walks on land and has bizarre human-like eyes. The leader of the expedition teams up with a circus owner who wants to exploit the weird creature but trouble ensues when the two men discover their crew has been slaughtered and the mutant is missing. Tales from the villagers come to light describing the local legend of a half-man, half-sea serpent, but what the expedition finds is an astounding seven-foot-tall walking octopus that has a lust for human blood! Now, the hunters have become the hunted and the race is on. Who will survive and what will be left of them...