J.K. Rowling has written a new 'Harry Potter' story.

The acclaimed author's latest work, 'Defence Against the Dark Arts teacher' - a biography of Dolores Umbridge - has been published on her website, Pottermore.

Rowling, 49, has previously said Umbridge is the character she dislikes the most, explaining: ''Her desire to control, to punish, and to inflict pain, all in the name of law and order, are, I think, every bit as reprehensible as Lord Voldemort's unvarnished espousal of evil.''

Umbridge is based on a real person, according to the author, who has previously said she once worked alongside a woman who was ''the most bigoted, spiteful champion of the death penalty''.

She continued: ''I have noticed more than once in life that a taste for the ineffably twee can go hand-in-hand with a distinctly uncharitable outlook on the world.

''A love of all things saccharine often seems present where there is a lack of real warmth or charity.''

What's more, Rowling has also revealed the origins of the character's name, saying: ''Dolores means sorrow, something she undoubtedly inflicts on all around her.

''Umbridge is a play on 'umbrage' from the British expression to 'take umbrage' meaning to take offence.''