Mortal Macedonian-Thessalian, eponymous founder of Pieria (the Muse-sacred region at the foot of Mt. Olympus). Father of Hyacinthus by the Muse Clio per Apollodorus 1.3.3. Not to be confused with King Pierus of Pella (a separate later figure) whose nine daughters challenged the Muses to a singing contest and were transformed into magpies — those Pierides are a different group from the Muses themselves who also bear that geographical epithet.