SOURCE: "The Brain Stealers of Mars" by John W. Campbell  (Thrilling Wonder Stories, December 1936)

DESCRIPTION: "The thushol are built of protoplasm--but infinitely more adaptable protoplasm. They can do something about it, make it take the form of a bone cell and be part of a thigh bone, or be a nerve cell in a brain..." ("The Brain Stealers of Mars" by John W. Campbell)

NOTES: The Thushol don't actually steal your brains but telepathically steal your thoughts and knowledge so they can appear as anything they like, even you. They have lived parasitically off the centaur-like Martians for eons and now wish to go to Earth to live off humans. Once they had been to Earth but returned because of our primitiveness. These visitors were responsible for the stories about dopplegangers.

HISTORY: Campbell uses this idea in several stories including another Penton and Blake tale about the krull and the famous Thing used in two movies. The title always sounded like that terrible Star Trek episode "Spock's Brain" (September 20, 1968) when Spock has his brain stolen. Only it's not.

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