Statue of a Young Satyr Wearing a Theater Mask of Silenos. Roman, about 1st century A.D. Restorations by Alessandro Algardi, 1628. (source)
Silenos (or Silenus) was, in Greek mythology, the tutor and companion of Dionysus, the god of wine and ritual ecstasy—as well as theater. He was generally portrayed as a shaggy forest man with the ears of a horse—sometimes the tail and legs too. He was, as a rule, so drunk that he had to be propped up by satyrs or carried by a donkey. When drunk he had the power of prophecy.