The film series will be based on a book published in 2001 which was originally billed as one of Harry Potter's textbook's.
The book, which was originally published in 2001 (between the fourth and fifth addition), was originally billed as one of Harry Potter's Hogwarts textbooks.
Warner Bros chief Kevin Tsujihara has reportedly persuaded Rowling to create the spin-off into a big-screen film series.
Last Week he told the New York Times that "three megamovies" are being planned, which will follow a "magizoologist" named Newt Scamander.
Scamander is the writer of a guide to magical creatures and his adventures will be the focus of the first film in the upcoming series.
The movie adaption was first speculated last September (2013)and Rowling commented that it even though it is set in the same wizard community of Harry Potter, "it is neither a prequel nor a sequel to the Harry Potter series, but an extension of the wizarding world".
Rowling also spoke with the Times and she praised Tsujihara for being a huge part of making the 'Fantastic Beats' adaptation happen.
"When I say he made Fantastic Beasts happen, it isn't P.R.-speak but the literal truth," she told the newspaper. "We had one dinner, a follow-up telephone call, and then I got out the rough draft that I'd thought was going to be an interesting bit of memorabilia for my kids and started rewriting!"
The spin-off story takes place seventy years before Harry Potter is ever introduced to the world, and will be set in New York City.
The original film franchises stars were Daniel Radcliffe, Emma Watson and Rupert Grint, but they will not be appearing in the spin-off versions.
Rowling's vision that the new film will be separate from the Potter stories will offer something new to Harry Potter fans without losing the fictional world that is universally loved. However, it could also unintentionally split the devoted wizard fans and find itself competing with Harry Potter, either way a new wizard adventure movie will give a fresh breath to the magical world, as ten years of the same old wizard can start to become tedious.
Rowling will pen a trilogy based on Harry Potter's textbook