"The Thing on the Doorstep" is a horror short story by American writer H. P. Lovecraft, part of the Cthulhu Mythos universe. It was written in August 1933, and first published in the January 1937 issue of Weird Tales.

Daniel Upton, the story's narrator, explains that he has killed his best friend, Edward Derby, and that he hopes his account will prove that he is not a murderer. He begins by describing Derby's life and career. Derby had been interested in the occult even as a very young boy. This is what caused him to befriend Upton. The two would chat about dark mythology in their spare time.