There isn't a definitive answer to this question as it is subjective. However, there are a few contenders for the title of shortest horror story ever written. One example is "The Last Word" by Edgar Allan Poe, which is only two sentences long. Another is "The Tell-Tale Heart" by Poe, which is only a little over 700 words. Both of these stories are considered to be some of the best examples of the horror genre, despite their brevity.
