Muggles' Guide to Harry Potter/Magic/Quintaped

Overview
No one knows anything very much about the Quintaped, which is apparently mythological. Quintapeds inhabit the island of Drear, which, of course, is unplottable.

Extended Description
The story of the Quintapeds appears in Fantastic Beasts and Where to Find Them. "Newt Scamander" writes:


 * Legend has it that the Isle of Drear was once populated by two wizarding families, the McCliverts and the MacBoons. A drunken wizarding duel between Dugald, chief of the clan McClivert, and Quintius, head of the clan MacBoon, is supposed to have led to the death of Dugald. In retaliation, so the story has it, a gang of McCliverts surrounded the MacBoon dwellings one night and Transfigured each and every MacBoon into a monstrous five legged creature. The McCliverts realized too late that the transfigured MacBoon were infinitely more dangerous in this state (the MacBoons had the reputation for great ineptitude at magic). Moreover, the MacBoons resisted every attempt to change them back into human form. The monsters killed every last one of the McCliverts until no human remained on the island. It was only then that the MacBoon monsters realized that in the absence of anyone to wield a wand, they would be forced to remain as they were for evermore.

Analysis
Quintapeds do not enter into the principal story at any point; we must assume that their existence is intended as something of an extra-value cautionary tale only. Given the information about the difference between Transfiguration and the Animagus transform, we may wonder how much intelligence the Quintapeds retained from their days as MacBoons.