The Shadow over Innsmouth is a horror novella by American author H. P. Lovecraft written in November–December 1931. It forms part of the Cthulhu Mythos using its motif of a malign undersea civilization and references several shared elements of the Mythos including place-names mythical creatures and invocations. The Shadow over Innsmouth is the only Lovecraft story which was published in book form during his lifetime.
