J K Rowling has given Harry Potter fans an extra special treat for Halloween and released new information based on the famous magical world. (Possible spoilers below)

The essays were published on Pottermore, a unique website built around the world of Harry Potter, and those with a membership to the site are able to sign in and read them now.

There are six new pieces added to the Harry Potter and the Order of the Phoenix interactive reading area, and a large section of the new writing uncovers the background of the much hated character, Dolores Umbridge.

Dolores Umbridge
Dolores Umbridge Warner Bros.

In her thoughts on the character, Rowling reveals that the ministry of magic official and one-time professor at Hogwarts, was based on a real-life person.

Rowling says that many years ago, she came into contact with "a teacher or instructor whom I disliked intensely on sight."

"The woman in question returned my antipathy with interest," she adds.

However, the author is quick to mention that she is being as vague as possible because she does not want her words misinterpreted in a way which could cause someone any hurt, and that "this woman was NOT 'the real Dolores Umbridge'. She did not look like a toad, she was never sadistic or vicious to me or anyone else."

Another section, labelled 'The Carriages', is based around the mystery of the skeletal horse-like creatures, Thestrals, and where they originate from.

Thestrals can only be seen by those who have "truly been touched by death," and in her writing, Rowling has finally provided the answer to the long-debated question of why Harry could only see them in his fifth year at Hogwarts.

Other new areas include an information section on every minister for magic since the position was created, a history of the infamous Azkaban prison, thoughts on divination professor Sybil Trelawney, and an introduction to the ancient wizarding practice of name seers.

Earlier this year, Rowling released other new content to the Pottermore website and published a short story about a grown-up Harry Potter attending the Quidditch World Cup final. It was the first time she had written about adult versions of her characters since the epilogue of the final book, Harry Potter and the Deathly Hallows.