The author returned to Twitter after a six month hiatus to post a stylised image of villain Lord Voldemort’s notorious Dark Mark.
She captioned the post: “Sometimes, darkness comes from unexpected places.”
She also included the hashtag #CursedChild, referring to the stage show follow-up to her hugely popular books and films, which revisits the Potter characters later on in their lives.
But while fans quickly got excited at the prospect of the show being turned into a film, the official Harry Potter fan site Pottermore seemed to have more of an insight.
They tweeted: “There is something exciting coming later on from @CursedChildNYC, but it’s not a movie…”
Harry Potter And The Cursed Child premiered in London’s West End in July 2016 and proved to be a huge success.
At the 2017 Laurence Olivier Awards it won a record-breaking nine awards and enjoyed similar success when it moved to Broadway in April 2018.
The play’s story begins 19 years after the events of The Deathly Hallows, the final book, and features Harry Potter as a senior figure at the Ministry of Magic while his son Albus Severus Potter is set to start at Hogwarts.