Tiny Stories
The “shortest horror story ever written” is usually attributed to Frederic Brown:
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.
[from Greg Ross, "Short-Shorts", Futility Closet, 16 September 2010.]
Smith's change certainly shortened Brown's original, but I think that Brown's original story was much stronger and more horrifying, although the paranoia of Smith's version is amusing.
They're neither so brief as the poignant six-word story [allegedly] by Ernest Hemingway:
For sale: Baby shoes. Never worn.
A few years ago I wrote a fifty-word story called "Morning Breaks", but I have to apologize because I can't locate the text right now. You'll be the first to know when I find it again.