Rearranging the letters of 'Rowling's "The Tales of Beedle the Bard"' (Unprinted Harry Potter's book) gives:
Her whole best strong detailed fable.
(by Aronas Pinchas) (2007) (pending approval)
Other related anagrams without their own page:
"JK Rowling" -> "Growl! Jink!" (by Kevin Sheldrick by hand) (2015) (pending approval)
"Harry Potter and the Deathly Hallows" -> "Hahah! Shallower n' deadly T.P trottery." (by Keir James Holling by hand) (2013) (pending approval)
"Harry Potter and the Deathly Hallows" -> "Last part, note! Why had orderly health?" (by Chris by hand) (2007) (pending approval)
"Harry Potter and the Deathly Hallows" -> "Halt a worthy trend -- spare the holy lad." (by George Thompson by hand) (2007) (pending approval)
"Harry Potter and the Deathly Hallows" -> "No-depth tale. Hardly worth the salary." (by Richard Grantham by hand) (2007) (pending approval)
"Rowling's 'Harry Potter and the Deathly Hallows'" -> "Hardly hogwash, her tale'll end in two-part story." (by Adie Pena using Anagram Genius) (2008) (pending approval)