Ministry of Magic Classifications

A classification is given by the Department for the Regulation and Control of Magical Creatures to all known Beasts, Beings and Spirits. These offer an at-a-glance guide to the perceived dangerousness of a creature. There are five categories.

The Five Categories

 * XXXXX: Known wizard killer / impossible to train or domesticate.
 * XXXX: Dangerous / requires specialist knowledge / skilled wizard may handle.
 * XXX: Competent wizards should cope.
 * XX: Harmless / may be domesticated.
 * X: Boring.

Behind the scenes

 * In Fantastic Beasts and Where to Find Them, Ron Weasley adds nine "X" to Acromantula's Classification. This is a reference to Ron's fear of spiders. This may also be contributed to by Aragog's offspring almost killing them, only being saved by the chance appearance of his father's car.
 * Despite the Basilisk being a XXXXX-ranked creature, meaning they are impossible to be domesticated, Parselmouths are able to control them. This is likely due instead to the incredibly dangerous nature of the creatures.

Appearances

 * Fantastic Beasts and Where to Find Them