Author JK Rowling has completed a set of handwritten fairytales which were mentioned in her last book, Harry Potter and the Deathly Hallows.
There will be just seven volumes of The Tales of Beedle the Bard and they will not be published.
One copy will be auctioned to raise money for her charity, The Children's Voice, and the author will give away the rest of them.
She said the books were a "wonderful way" to say goodbye to Potter.
"People kept saying to me 'you'll be glad to have a break from writing', when of course I wasn't taking a break at all," added the writer.
"I was literally writing out - as these are handwritten books - these new stories which has been a wonderful way to say goodbye. It's like coming up from a deep dive."
The fairytales, which were illustrated by Rowling herself, are the first works she has written since the Potter novel was published in July.
The Tales of Beedle the Bard was left to Potter character Hermione by Hogwarts school headmaster Dumbledore.
The seven books are all handwritten by the author
In a recent US book tour, the author revealed that Dumbledore was gay.
Rowling said she had always seen him as gay in her mind.
"No-one ever asked me had he ever been in love or fallen in love. People were very focussed on what happens to Harry so I had never been asked a direct question.
"And because to answer it would immediately flag up an infatuation with what happens in book seven, I never said it."
The new book will be auctioned at Sotheby's in London on 13 December with a starting price of £30,000, although it is expected to sell for a lot more.
Harry Potter book sales already stood at 325 million copies even before the seventh novel came out - it broke records on both sides of the Atlantic by selling 11 million copies in 24 hours.
It was published simultaneously in more than 90 countries.
JK Rowling and the makers of the Harry Potter films, Warner Bros, are suing a US publisher over its plans to release a book version of a popular website dedicated to the boy wizard.
The legal action claims that RDR Books will infringe on Rowling's intellectual property rights if it publishes the 400-page Harry Potter Lexicon.
It adds that this would interfere with her plans to write her own definitive Harry Potter encyclopaedia.
RDR Books publisher Roger Rapoport said the suit dismayed him and dismissed any notion it could compete with any official encyclopaedia written by Rowling.