A fictional book of magic invented by H. P. Lovecraft, which features in his Cthulhu Mythos stories. Lovecraft cites the meaning of the title as being derived from nekros (corpse), nomos (law), eikon (image): "An image of the law of the dead". A more prosaic (but probably more correct) translation, is via a declination of nemo (to consider): "Concerning the dead".
According to Lovecraft's account the original, called Al Azif (the sound of nocturnal insects, said in folklore to be the conversation of demons), was written by the mad Arab, Abdul Alhazred, and contains an account of the Old Ones, their history, and descriptions of how they may be summoned. A number of translations were made over the centuries - the Elizabethan magician, John Dee was supposed (by Lovecraft) to have possessed a copy. The book is now mentioned in various places in fiction but always as being very rare; there are copies in the British Museum, the Sorbonne, and the library of Miskatonic University in Arkham, Massachusetts. The book, like other fictional works such as The King in Yellow is dangerous to read, being almost inevitably destructive of ones health and sanity, and is kept under lock and key in these libraries.
Many later fantasy and horror writers have mentioned the Necronomicon in their own stories: two examples are a passage in Gene Wolfe's novel "Peace", in which a book of necromancy being forged by a character is not named, but is obviously the Necronomicon, and Terry Pratchett's humorous version, the "Necrotelecomicon" (the book of phone numbers of the dead)
Even though Lovecraft himself insisted the book was pure invention (and other writers invented passages from the book in their own works), there are accounts of some people actually believing the Necronomicon to be a real book. This issue was confused in the late 1970s by the publication of a book purporting to be a translation of the real Necronomicon. This book, by the pseudonymic "Simon", published by Schlangekraft and then in Avon paperback, connected the Lovecraft mythology to Sumerian Mythology. This connection between fiction and a historical religion persists to this day.
** mention in the paragraph above that no "real" copies of the book exist. Any necronomicon book that was published is an entire fabrication. **
In the movies Evil Dead II and Army of Darkness the "Necronomicon Ex Mortus" appears as an evil book of magic; in the first Evil Dead, a recording of an academic reading from the Necromicon caused all of Ash's later trouble. In the Evil Dead mythology, this book was written three thousand years ago and disappeared circa 1300 AD.
see: false document