Brown, Fredric – “The Last Martian” (1950)
The setup: a reporter is called to a bar to interview a man who claims to the last living Martian.
The body: the reporter buys the guy (Yangan Dal) a drink, and is rewarded with his story: Mars had been a thriving world of 3 billion souls up until recently, when a mysterious desert plague reduced the population to 100 million. Yangan Dal’s memory is hazy at best, but he is sure that some sort of further calamity finished off the rest of the race, because he remembers waking up one day and finding bodies littered throughout the city, particularly in one stadium centered on some sort of mechanism – the activation of which send the Martian’s mind into his new body, that of Howard Wilco, earthling (leading to the quip “This isn’t I, this body I’m in. You don’t think Martians would look exactly like humans, do you?” which might be the most worthwhile thing to take from this story). The reporter advises Howard to put this dream out of his mind and go home to his wife.
The twist: the mechanism purposefully propelled the minds of the Martians away from their dying world and into unsuspecting Earthlings. The reporter, his editor, and the bartender are all Martians, and they feel pity and condescension for this new confused guy, who doesn’t understand or remember anything because he had been locked in an asylum for the feeble-minded. I’m surprised they never filmed a sub-par episode of The Twilight Zone based on this one.