Villain(s)  Brain-shaped alien

Actor(s):  John Agar, Joyce Meadows, Robert Fuller, Thomas Browne Henry

Brief Description  The Brain from Planet Arous (1957) is a quintessential low-budget, black-and-white science fiction film about an evil, giant floating alien brain that possesses an Earth scientist to achieve world domination. Directed by Nathan Juran (who used the pseudonym "Nathan Herz" out of embarrassment) and starring B-movie staple John Agar, the film has since earned a beloved cult following for its campy execution, absurd premise, and memorable special effects.

Plot:
Nuclear scientists Steve March (John Agar) and Dan Murphy (Robert Fuller) detect mysterious radiation pulses coming from Mystery Mountain. They track the source to a deep cave. Inside the cave, they encounter Gor, a giant, translucent, glowing alien brain from the planet Arous. Gor immediately blasts Dan to death with energy rays and forcibly merges into Steve's body to take control of his mind and physical form. Back at home, a possessed Steve begins acting erratic, aggressive, and power-hungry. He violently makes advances toward his fiancée, Sally Fallon (Joyce Meadows), and displays sinister, maniacal laughter. Sally and her father become highly suspicious and return to the cave. There, they meet Vol (sometimes referred to as Val or Paul), an intergalactic investigator brain sent to capture the criminal Gor.

To stay hidden while helping them, Vol inhabits the body of Sally’s family dog, George. Gor uses Steve's scientific access to meet with military officials, demonstrating his immense power by telekinetically blowing up an atomic airplane in mid-air. He threatens world leaders with absolute destruction if they do not surrender global control to him. Vol reveals to Sally that Gor must periodically leave Steve's body to breathe and re-energize, making him briefly vulnerable. Vol also identifies Gor's physical weak spot: the Fissure of Orlando at the back of the brain. Armed with this knowledge, Sally waits for Gor to exit Steve's body in his lab. She corners him and destroys the alien tyrant by repeatedly hacking his fissure with an axe, freeing Steve and saving the Earth.