In 1764, Horace Walpole published his first ever novel, The Castle of Otranto. After the publication of this novel, he lead his readers to believe that this story was non-fiction and that all of the twists and turns that occured throughout the plot were true. Eventually, in the second edition of The Castle of Otranto, it was revealed that the entire novel was utter fiction. (Which drastically affected the sales for the worse).
Regardless of Walpole’s little prank, his book is still recognised as the first ever horror (or gothic) novel to have been written…ever.