UPDATE: Read the full Halloween Harry Potter tale from J.K. Rowling here.

Harry Potter fans rejoice!

J.K. Rowling will be releasing a new tale from the Harry Potter universe exclusively on TODAY.com for Halloween this Friday, so visit the site tomorrow morning to get your fix.

The author has periodically released new pieces through her website Pottermore.com and TODAY.com, letting fans get to know little-known characters and corners of the Harry Potter world. This Halloween, she'll reveal the story behind Dolores Umbridge, one of the most malicious characters in the Harry Potter universe.

Check out some of Rowling's past writings from Pottermore.com, including her profile of a singing sorceress and a Daily Prophet story about Harry Potter's reunion with his friends at the Quidditch World Cup Finals.