The Monster of Piedras Blancas (1959)

The monster, which looks like a snarling "Creature from the Black Lagoon," invades a sleepy seaside town. The lighthouse keeper, widowed and estranged from the town folk, has been secretly leaving food out for the monster for years, unaware of its blood lust. When the monster's appetite outstrips the keeper's ability to serve it, bloodless decapitated corpses start to show up.