necronomicon or the "book of the dead" is a fictional creation by the most awesome of horror/macabre writers H.P lovecraft.referenced in his early works concerning "the old ones" in 1924.this book took a life of its own and many people were convinced this made up grimoire to be a real text.
some clever people made a movie based on this disturbing piece of fiction.based on the character "mad" abdul alhazred.

from y/t:
The Necronomicon is a fictional book from the stories of horror writer H. P. Lovecraft. It was first mentioned in Lovecraft's 1924 short story "The Hound", written in 1922, though its purported author, the "Mad Arab" Abdul Alhazred, had been quoted a year earlier in Lovecraft's "The Nameless City".[1] Among other things, the work contains an account of the Old Ones, their history, and the means for summoning them.

Other authors such as August Derleth and Clark Ashton Smith also cited it in their works; Lovecraft approved, believing such common allusions built up "a background of evil verisimilitude." Many readers have believed it to be a real work, with booksellers and librarians receiving many requests for it; pranksters have listed it in rare book catalogues, and a student smuggled a card for it into the Yale University Library's card catalog.

This a three film adoptation that is the mythos of HP Lovecraft ,