The Shadow Out of Time

A young professor from the fictional Miskatonic University learns that aliens, the Yith, are possessing the bodies of humans to learn about the history and culture of the Earth.  He soon becomes convinced that he is also possessed, but those around him fear he is simply insane...

Howard Phillips Lovecraft (1890-1937) was an American author of horror, fantasy and science fiction, especially the subgenre known as weird fiction.  As early as the 1940s, Lovecraft's work had developed a cult following for his Cthulhu Mythos, a series of loosely interconnected fiction featuring a pantheon of humanity-nullifying entities, as well as the Necronomicon, a fictional grimoire of magical rites and forbidden lore. Stephen King called Lovecraft "the twentieth century's greatest practitioner of the classic horror tale."