Dr. Eric Vornoff, with the help of his mute assistant Lobo, captures twelve men for a grisly experiment; His goal to turn them into supermen using atomic energy. Reporter Janet Lawton, fiancée of the local lieutenant, vows to investigate Vornoff's supposedly haunted house.
Two fishing scout pilots make a horrifying discovery when they encounter a second Godzilla alongside a new monster named Anguirus. Without the weapon that killed the original, authorities attempt to lure Godzilla away from the mainland. But Anguirus soon arrives and the two monsters make their way towards Osaka as Japan braces for tragedy.
Japan is thrown into a panic after several ships are sunk near Odo Island. An expedition to the island led by Dr. Kyohei Yamane soon discover something far more devastating than imagined in the form of a 50 meter tall monster whom the natives call Gojira. Now the monster begins a rampage that threatens to destroy not only Japan, but the rest of the world as well.
Ann Dexter, daughter of an itinerant Haiti waterfront character, Carl Dexter, brings a golden idol, which her father her stolen at a voodoo ceremony, to Bill Buchanan, who is known along the waterfront as a man eternally on a treasure hunt. He agrees to let Ann accompany him in search of the treasure after a native he befriended gives him directions and certain voodoo secret charms. They follow an underwater passage to an island where they find a Pagan tribe. They learn that the golden idol is a burial symbol representing the dead and that hundreds of idols are at the bottom of the sacred burial lake.
Julie, an American on vacation in Mexico, spots a giant, one-eyed amoeba rising from the ocean, but when she tries to tell the authorities, no one believes her. She finally teams up with a marine biologist in an attempt to destroy it.
Eight people at a remote Scottish inn find themselves confronted by a woman from Mars, who has landed her flying saucer for repairs but intends to soon conquer the Earth and enslave its men for breeding purposes.
When scientists exploring the Amazon River stumble on a “missing link” connecting humans and fish, they plan to capture it for later study. But the Creature has plans of his own, and has set his sights on the lead scientist's beautiful fiancée, Kay.
Atomic scientist/pilot Doug Martin is missing after his plane crashes on an reconnaissance mission after a nuclear test. Miraculously appearing unhurt at the base later, he is given sodium amethol, but authorities are skeptical of his story that he was captured by aliens determined to conquer the Earth with giant monsters and insects. Martin vows to use existing technology to destroy them.
London, 1888: on the night of the third Jack the Ripper killing, soft-spoken Mr. Slade, a research pathologist, takes lodgings with the Harleys, including a gloomy attic room for "experiments." Mrs. Harley finds Slade odd and increasingly suspects the worst; her niece Lily (star of a decidedly Parisian stage revue) finds him interesting and increasingly attractive. Is Lily in danger, or are her mother's suspicions merely a red herring?
A scientist takes the brain of dead man and revives it via electrodes as it lays suspended in a tank of liquid. Soon, the brain grows to possess enormous psychic powers and inflicts its personality upon the doctor who saved it, creating a "Jekyll and Hyde" paradigm.
Ro-Man, an alien robot who greatly resembles a gorilla in a diving helmet, is sent to earth to destroy all human life. Ro-Man falls in love with one of the last six remaining humans, and struggles to understand how his programming can instruct him to kill her while his heart demands that he can't.
A scientist develops a formula which will cause animals to regress to the form of their primitive ancestors, and tries it on himself with disastrous results.
A mad scientist, Dr. Aranya (Jackie Coogan), has created giant spiders in his Mexican lab in Zarpa Mesa to create a race of superwomen by injecting spiders with human pituitary growth hormones. Women develop miraculous regenerative powers, but men mutate into disfigured dwarves. Spiders grow to human size and intelligence.
Author and amateur astronomer John Putnam and schoolteacher Ellen Fields witness an enormous meteorite come down near a small town in Arizona. Putnam becomes a local object of scorn when, after examining the object up close, he announces that it is a spacecraft, and that it is inhabited...
The Office of Scientific Investigations tracks down the source of increased magnetism and radioactivity in Los Angeles, and discovers that a man-made isotope is consuming available energy from nearby mass every few hours, doubling its size in the process. Although microscopic, it will soon become big enough to destroy Earth; and how to stop it is yet to be determined. The film's Deltatron special effects footage is taken from the 1934 German sci-fi film GOLD.
Warned that it is haunted, a skeptical young couple buy a rundown yacht and fix it up to be their home-on-the-sea, only to slowly realize that it really is haunted.