The Case of Charles Dexter Ward
He has a number of similarities with later characters created by Lovecraft, in particular Joseph Curwen, the villain of "The Case of Charles Dexter Ward": Both were improbably old, such that no one remembered when they were young; possessed vaguely defined but powerful abilities oriented around storing the dead in peculiar objects and calling them forth to serve them; and had access to ancient coinage of precious metals (as do the Whateleys in "The Dunwich Horror").