The bestselling British author triggered a flurry of speculation Sunday when she tweeted that she was working on a novel while "tweaking a screenplay."
She sent fans into a frenzy Monday when she dropped hints that some construed as the return of her famed boy wizard.
"Cry, foe! Run amok! Fa awry! My wand won’t tolerate this nonsense," Rowling teased.
As fans scratched their heads over the clues, and responded with their best answers, Rowling dropped more hints that she's working on the already-announced Harry Potter spin-off film Fantastic Beasts and Where to Find Them.
Newt Scamander is the main character in the 2001 book of the same name. His name appears in the Harry Potter books as the author of a textbook used to instruct young wizards at Hogwarts.
When Warner Bros. confirmed the Fantastic Beasts last September, Rowling said in a statement the movie "is neither a prequel nor a sequel to the Harry Potter series, but an extension of the wizarding world."
She said the story would begin in New York 70 years before the start of the boy wizard's tale, and fans can expect some Harry Potter-like characters and creatures familiar to appear.
Warner Bros. was behind eight Harry Potter movies released between 2001 and 2011 that took in $7.7 billion US at the global box office.
Since the film series wrapped up, the company has been involved in related ventures, including a Harry Potter studio tour near London, Universal's Wizarding World of Harry Potter theme park in Orlando and the Pottermore website.
Rowling keeping busy
Screenwriting is the latest in a string of new ventures for Rowling since she finished writing the Harry Potter series, which has sold more than 450 million copies around the world.
She has published a novel for adults, The Casual Vacancy, and two detective thrillers under the pseudonym Robert Galbraith.
Rowling said the idea for a Fantastic Beasts film came from Warner Bros., and she soon realized she could not entrust another writer with her creation.
"Having lived for so long in my fictional universe, I feel very protective of it," she said. "I already knew a lot about Newt.
"As I considered Warner's proposal, an idea took shape that I couldn't dislodge. That is how I ended up pitching my own idea for a film to Warner Bros."