The centaurs are a race from Greek mythology. They are part human and part horse, with a horse's body and a human head and torso in place of the horse's head and neck.
Dwelling in the mountains of Thessaly and Arcadia, the centaurs were the offspring of Ixion and Nephele (the rain-cloud). Alternatively, the centaurs were the offspring of Kentauros (the son of Ixion and Nephele) and some Magnesian mares or of Apollo and Hebe. It was sometimes said that Ixion planned to have sex with Hera but Zeus prevented it by fashioning a cloud in the shape of Hera. Since Ixion is usually considered the ancestor of the centaurs, they are often referred to as the Ixionidae.
They are best known for their fight with the Lapithae, caused by their attempt to carry off Hippodamia on the day of her marriage to Peirithous, king of the Lapithae, himself the son of Ixion. Theseus, who happened to be present, assisted Pirithous, and the Centaurs were driven off (Plutarch, Theseus, 30; Ovid, Metam. xii. 210; Diod. Sic. iv. 69, 70).
In later times they are often represented drawing the car of Dionysus, or bound and ridden by Eros, in allusion to their drunken and amorous habits. Their general character is that of wild, lawless and inhospitable beings, the slaves of their animal passions. Two exceptions to this rule were Pholus and Chiron, who were wise and kind centaurs. They are variously explained by a fancied resemblance to the shapes of clouds, or as spirits of the rushing mountain torrents or winds. As children of Apollo, they are taken to signify the rays of the Sun.
It is suggested as the origin of the legend, that the Greeks in early times, to whom riding was unfamiliar, regarded the horsemen of the northern hordes as one and the same with their horses; hence the idea of the Centaur as half-man, half-animal. Like the defeat of the Titanss by Zeus, the contests with the Centaurs typified the struggle between civilization and barbarism.
In early art they were represented as human beings in front, with the body and hind legs of a horse attached to the back; later, they were men only as far as the waist. The battle with the Lapithae, and the adventure of Heracles with Pholus (Apollodorus, ii. 5; Diod. Sic. iv. li) are favourite subjects of Greek art (see Sidney Colvin, Journal of Hellenic Studies, i. 1881, and the exhaustive article in Roscher's Lexikon der Mythologie).
There are other hybrid races, like centaurs, that show up in mythology such as the mermaids and the satyrs. A general 'taur form in modern science fiction and fantasy literature is a six limbed being, using four for locomotion and two for manipulation. They are based upon many different animals, not just horses and humans. In many, the 'human' part is in fact an anthropomorph of the base animal, such as in the wemic and bariaur.