JK Rowling has had 7 book adaptions, the 7 Harry Potter books, one of them just happened to be split into two films. And fantastic beasts and where to find them was not an adaption, those were written as scripts and therefore weren't adapted from a book.
Rawhead Rex (UK, 1986), Hellraiser (UK, 1987), Nightbreed (1990), Candyman (1992), Lord of Illusions (1995), The Midnight Meat Train (2008), Book of Blood (UK, 2009), Dread (UK, 2009).
JK Rowling has had 7 book adaptions, the 7 Harry Potter books, one of them just happened to be split into two films. And fantastic beasts and where to find them was not an adaption, those were written as scripts and therefore weren't adapted from a book.
Tom Clancy? (6)
Charles Dickens (40, including several remakes)
Louis L'Amour (16)
Elmore Leonard (29)
What a cr*ptastic list