The Miskatonic River is a fictional New England river in the writings of H. P. Lovecraft. It is also the name of a river system, the Miskatonic Valley. The equally fictitious Miskatonic University in Arkham is named after this river. The Miskatonic was first mentioned (as "Miskatonic Valley") in Lovecraft's "The Picture in the House" (1920).
The fictional communities of Arkham and Dunwich, Massachusetts are said to be located along the Miskatonic. In "The Colour Out of Space" (1927), the narrator claims that there is a "small island in the Miskatonic where the devil held court beside a curious stone altar older than the Indians."