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In the 1970s, Forrest Ackerman sold this story to Vertex for $100:

"Cosmic Report Card: Earth F"

He resold it four times for the same amount, and it’s been translated into three languages.

The “shortest horror story ever written” is usually attributed to Frederic Brown and is a s follows:

"The last man on Earth sat alone in a room.

There was a knock on the door."

Ron Smith shortened this further by changing knock to lock.