"The Beast in the Cave" is a short story by American horror fiction writer H. P. Lovecraft. The first draft was written in the Spring of 1904, with the final draft finished in April 1905, when Lovecraft was fourteen.  It was first published in the June 1918 issue of the amateur press journal The Vagrant. 
A man touring Mammoth Cave separates from his guide and becomes lost. His torch expires and he is giving up hope of finding a way out in the pitch dark, when he hears strange non-human footsteps approaching him. Thinking it to be a lost mountain lion or other such beast, he picks up a stone and throws it toward the source of the sound. The beast is hit and crumples to the floor. The guide finds the protagonist, and together they examine the fallen creature with the guide's torchlight. The creature mutters in its last breaths and they see its face, discovering that it is in fact a pale, deformed human, who had also become lost in the cave many years ago.