In mythology, centaurs were half man, half which other creature?

Centaur, Greek Kentauros, in Greek mythology, is a race of creatures, part horse and part man, dwelling in the mountains of Thessaly and Arcadia. Traditionally they were the offspring of Ixion, king of the neighboring Lapiths, and were best known for their fight (centauromachy) with the Lapiths, which resulted from their attempt to carry off the bride of Pirithous, son and successor of Ixion.

Source: Britannica