Fantastic Beasts and Where to Find Them by Newt Scamander contains descriptions of 27 magical beasts, written by a renowned magizoologist.
Quidditch Through the Ages by Kennilworthy Whisp, gives a comprehensive history of the game and its rules as well as a rousing description of the top teams in the sport.
(Both books are graced with the doodles of Harry Potter, Ron Weasley, and other students at Hogwarts who couldn’t resist.)