Not quite as big as a giant, but with even less intelligence, trolls can grow up to twelve feet tall and have a propensity towards violence. Weighing up to a tonne, trolls have enormous strength and an apparent taste for human flesh. Classified as a ‘beast’ rather than a ‘being’ thanks to their low IQ, some skilled magical linguists are able to communicate with trolls. Harry Potter and Ron Weasley managed to take down a troll that had been 'let loose' in Hogwarts in their first year.