The bespectacled boy wizard made his final appearance in Harry Potter and the Deathly Hallows in July 2007.
She has never ruled out a comeback, so fans got their wands in a whirl when the 49-year-old tweeted on Monday:
Cry, foe! Run amok! Fa awry! My wand won't tolerate this nonsense.
- J.K. Rowling (@jk_rowling) October 6, 2014
Followers were quick to see the message as an anagram and claimed it translated as: "Harry returns! Won't say any details now. A week off. No comment."
JK then followed up with a series of tweets challenging them to solve the riddle until Emily Strong, a PhD student at the University of Sheffield who is as a lover of 'all things Harry Potter', tweeted the solution:
- Emily Strong (@EmyBemy2) October 7, 2014
JK was quick to confirm she was right. Tweeting:
.@EmyBemy2 YES!!!!!!!!!!!! People, we have a winner!
- J.K. Rowling (@jk_rowling) October 7, 2014
Newt Scamander is the star of her Harry Potter spin-off, Fantastic Beasts And Where To Find Them, which is set to become a film trilogy. Set in 1920s New York, he is a magizoologist - dealing with magical creatures.
After all the kerfuffle, JK tweeted: "Thank you, thank you, for being the kind of people who get excited about an anagram."
A statement on the author's website says in reply to the question of whether there will be another Harry Potter novel: "I have always refused to say 'never' to this question, because I think it would be foolish to rule out something I might want to do in a few years' time.
"However, I have no immediate plans to write another Harry Potter novel, and I do think that I have rounded off Harry's story in the seven published books."
The Harry Potter series of seven books has sold more than 450 million copies.