The Roman emperor Caligula rode Incitatus, a talking horse.
Centaurs are creatures with the torso, arms, and head of a human and the lower body and legs of a horse. While most centaurs prefer to relax and enjoy life in the form of parties, some such as Chiron show a more mature tone.
Icthyocentaurs are centaurs and hippocampi like creatures with the lower part of a hippocampus and the upper part of a man. They also have blue or green skin.
Hippocampi are creatures whose front half is that of a horse and their back half is that of a giant fish. They also have colours similar to a rainbow.
Hippalektryons ("rooster ponies") are an endangered species of magical horses. They have the front half of a horse and the back half of a rooster. Their rear feet have huge yellow claws. Their tails are feathery and their wings are red.
Unicorns are a magical species of horses who didn't was made for war or battles. In truth, they are very important to medicine as their silver and gold horns could be used to a multitude of forms as well powder or drought.
Fire-Breathing Horses are a magical species of horses than can breathes out fire through their nostrils. Percy notes that the fire must hurt the horses' sinuses. They might have manes of fire because a little girl looked at them and said, "Pony on fire!"
Flesh-Eating Horses are horses that feed on the flesh of other animals or mortals. They also hate to bathe themselves.