Centaurs are probably one of the most famous mythological creatures in myth. They are described as having the body of a horse, but upperbody of a man.
There are different variations of the centaurs' origin. One story is that they were the descendants of Centaurus (the son of Apollo and Stilbe). Centaurus was the brother of Lapithus. Another story is that they came from Ixion (the king of Thessaly) and a cloud created by Zeus that was made to look like Hera.
I'd like to tell you that they were very intelligent, deep, beings that often looked to the stars for answers, but unfortunately J.K. Rowling was quite wrong. Centaurs are often said to have been wild and savage and infamous for their lustfullness and drunkeness. They were often guilty of physical, even sexual, violence.
The ancients were too fond of horses to consider the union of horses and men as forming a very degraded compound, and accordingly the Centaur is the only one of the monsters of antiquity to which any good traits are assigned. The Centaurs were admitted to the companionship of man, and at the marriage of Pirithous (king of Lapiths) with Hippodamia they were among the guests. When Eurytion and the other centaurs had a little bit too much wine and got drunk, they tried to kidnap and rape the bride and the other Lapith women. Peirithoüs, aided by his other guests (including Theseus, Peleus and Nestor) drove the centaurs out of Thessaly.
Not all centaurs were bad, however. Chiron was not only immortal, but renowned for his skill in hunting, medicine, music, and the art of prophecy. The most distinguished heroes of Greek history were his pupils. He tutored Achilles, Aesulapius, Jason, and Actaeon (among others).
Chiron was the son of the Titan Cronus and Philyra, who was the daughter of Oceanus and Tethys. Philyra, who was raped by Cronus in the form of a stallion, became ashamed when she saw that she had given birth to a centaur. The gods took pity on her and turned her into a linden tree.
Chiron was friends with Heracles, but it was that friend that brought his own death. As Heracles fought against the centaurs during his fourth labor, the hero accidently wounded his Chiron. Chiron was hit with an arrow smeared with the venom of the monster Hydra. Since Chiron was immortal, he couldn't die and spent a lot of time in great agony because of the venom. Later on, during Heracles' eleventh labor, the son of Zeus freed the Titan Prometheus from his chain. Chiron asked the gods to transfer his immortality to Prometheus, and his wish was granted and Chiron finally found release from his pain. Chiron was the wisest and most just of all the centaurs, and at his death Zeus placed him among the stars as the constellation Sagittarious.