Ronan, Bane, and Firenze
These three figures are centaurs who Harry meets in the forest during detention. Centaurs can foresee the future in the stars and they know of Voldemort's planned return. But while Ronan and Bane want to stay out of human affairs, Firenze thinks Voldemort's evil is too great to not do anything about. He's willing to help humans and even allows Harry to ride on his back.