"The Moon Bog" is a short story by American horror fiction writer H. P. Lovecraft, written in or before March 1921 and first published in the June 1926 issue of Weird Tales. The story was written to order, as an after-supper "shocker" for a Hub Club gathering of amateur journalists in Boston on March 10, 1921. The meeting had a St. Patrick's Day theme. Like Barry, Lovecraft had dreams of buying back his ancestors' home in England. This same theme is treated with greater depth in Lovecraft's "The Rats in the Walls" (1923).