The Tales of Beedle the Bard (JK Rowling, 2008) is a set of five fairy tales set in the world of Harry Potter. They're purportedly translated from the original runes by Hermione Granger, though we don't get any notes or commentary from her. (Much to my disappointment, as Hermione is by far my favorite character. Surprise, surprise, I root for the bookish know-it-all.) Each tale, however, is followed by commentary by Albus Dumbledore, allowing Rowling to bring some snark and get in some explicit digs against censorship, bowdlerization, and bigotry.
Some reviewers on Amazon complain that it's a slight book, which I don't think is fair. It's supposed to be bedtime stories beloved by wizarding children, so it wouldn't make sense for it to be as long and intricate as the later Harry Potter books. It's a charming, quick read (I finished it in about 45 minutes), and I look forward to sharing it with my daughter in two or three years when she's old enough for Harry Potter and the Philosopher's Stone. (Yes, we have the British editions. We bought the first two in Canada, and my husband ordered the rest from amazon.co.uk so our set would match.)