The Fantastic Beasts and Where to Find Them textbook, written by J.K. Rowling as Newt Scamander, describes a troll as ‘a fearsome creature up to twelve feet tall and weighing a tonne’. They originated in Scandinavia, Newt explains, and they are strong, unpredictable creatures with a propensity towards violence and stupidity.

In fact, the stupidity of trolls is what caused them to be officially listed as beasts, after early wizarding attempts at classification identified ‘any member of the magical community that walked on two legs’ as a ‘being’, distinct from the ‘beasts’ that flew or crawled on four legs.

According to Fantastic Beasts, trolls were used by goblins to demonstrate how absurd this method of classification was. When it was later overturned, the trolls’ lack of understanding was key to their being termed ‘beasts’.