The Necronomicon is a fictional grimoire created by author H.P. Lovecraft in his stories, particularly noted in the Cthulhu Mythos. It is often described as a book of forbidden knowledge, containing dark secrets and spells that can summon ancient cosmic entities. In Lovecraft's universe, the Necronomicon is said to have been written by the 'Mad Arab' Abdul Alhazred and is feared for its ability to drive readers insane. Its influence extends beyond literature, inspiring films, games, and various forms of popular culture, making it a significant artifact in horror fiction.