Pierus (Ancient Greek: Πίερος), in Greek mythology, is a name attributed to two individuals.
Pierus, the eponym of Pieria, son of Makednos and father by either Antiope of Pieria or Euippe (of Paionia) of the Pierides, nine maidens whom he named after the nine Muses believing that their skills were a great match to the Muses. They afterwards entered into a contest with the Muses, and being conquered, they were transformed into magpies. Pierus is sometimes said to have been father of Linus or Oeagrus and therefore the grandfather of Orpheus.
Pierus, son of Thessalian Magnes and Meliboea, was the lover of muse Clio and father of Hyacinth in some accounts, and Rhagus. Pierus was loved by muse Clio because Aphrodite had inspired her with the passion, as a punishment for deriding the goddess' own love for Adonis.
According to Solinus (9.10), Pierus was unrelated and older than Makednos.
