Satyrs were male hybrid creatures who were part horse and part human. They stood and walked upright, unlike the quadruped, half-horse Centaurs to whom they were akin, and in their original, traditional form, they had horses’ tails, long hair and beards, horses’ ears, bulbous foreheads, and snub noses. Artistic representations also showed them sometimes with the legs and hooves of a horse as well as with enlarged, erect penises. It was only in the Hellenistic Period (after 323 BCE, the death of Alexander the Great) that Satyrs, in an assimilation to the rustic god Pan, took on a goatlike appearance, having shorter tails and sprouting horns.
Satyrs, who in earliest times were indistinguishable from Silens, were woodland spirits or daemons that lived in the wild, being found in mountains, forests, and caves alongside Nymphs with whom they cavorted and whom these lusty creatures amorously pursued. Lustfulness, enthusiasm for wine, and a propensity for mischief were characteristic of them. Silens, on the other hand, came to be viewed as elderly Satyrs.
Alongside Nymphs, both Satyrs and Silens formed the typical entourage of the shape-shifting god Dionysus. The best-known Satyr in Classical mythology was also the most tragic of them. This was Marsyas, who had found the flute cast aside by the goddess Athena, and, when he discovered that he had a talent for playing the instrument, he made the terrible mistake of challenging Apollo to a music contest. As a consequence of his pridefulness, he was flayed alive. Another Satyr, his name unknown, pursued the Danaid Amymone, but was driven off by Poseidon, who then took up in the pursuit of the maiden himself.
Source: Classical Mythology A – Z