Great God Pan
Fantasist author Arthur Machen of such works at the Great God Pan is mentioned in many of Lovecraft's stories. The Great God Pan is a novellette published in 1894 and is probably the inspiration for "The Dunwich Horror" since it involved the sexual union between a human woman and Pan, the god, which produced a female child, Helen Vaughn, who destroys all around her until she dies horribly.
[The Dunwich Horror - H.P.L.]
[The Call of Cthulhu - H.P.L.]
[The Whisperer in Darkness - H.P.L.]
See also: Arthur Machen