Move Under Ground is a horror novel mashup by American writer Nick Mamatas, which combines the Beat style of Jack Kerouac with the cosmic horror of H. P. Lovecraft's Cthulhu Mythos. It is available as a free download via a Creative Commons license, CC BY-NC-ND 2.5 according to the License information in the CC version of the book.

Nick Mamatas is an American horror, science fiction and fantasy author and editor for Haikasoru's line of translated Japanese science fiction novels for Viz Media. His fiction has been nominated for a number of awards, including several Bram Stoker Awards. He has also been recognised for his editorial work with a Bram Stoker Award, as well as World Fantasy Award and Hugo Award nominations. He funded his early writing career by producing term papers for college students, which gained him some notoriety when he described this experience in an essay for Drexel University's online magazine The Smart Set.