Centaurs are magical creatures that are horses below the waist and humans above the waist. They are the hipsters of the wizarding world, rarely seen without berets and never sunglasses. Anyone dumb enough to insult a centaur would find themselves surrounded by them, beaten to a pulp and made into bongo skins. Centaurs are unusually fast (due to their horse half). Herdes of centaurs can be found in the Forsaken Forest where they guard it and slopilly maintain it.
Centaurs can be found in each of the Barry Trotter books.