“I’ve just finished the fourth Galbraith novel, Lethal White, and I’m now writing the screenplay for Fantastic Beasts 3,” Rowling said, referring to thrillers she writes under the pseudonym Robert Galbraith.
On her role as one of the producers:
“Warner Bros. and David Yates, the director, have always let me have my say, though not necessarily the final word,” Rowling said. "That’s true of all the producers, of whom I’m only one: our input is taken seriously but it is very much a collaborative effort."
In an interview with Collider, Depp confirmed his involvement in the third film, revealing that he’s ““[looking] forward to the next installment, which I think we start the middle of next year.”
He expanded on how Rowling approached him for the role, for which he was officially cast in 2016 amidst a contentious divorce and allegations of abuse:
“It was amazing. It came out of nowhere. Someone said J.K. Rowling would like to talk to me. I spoke to a few producers and the director and to J.K. and had long conversations basically about the Grindelwald character. J.K. said something I did not expect to hear because obviously her detail to her characters and those wizarding worlds is astonishing. The fact that she said, ‘I can’t wait to see what you do with the character.’
Just to hand it off to me with that degree of trust, I was really touched, blown away by that. So I jumped into locating the character and I had my ideas. I came in and it all seemed to work out. Grindelwald is an interesting character. His intentions in his mind are for the greater good, but there have been other people in world politics and such who felt the same way. [chuckles] He’s very dedicated to his beliefs. He’s not a fun character; he’s not funny.”