Pierus, in Greek mythology, refers to two individuals.
One of them was the son of Makednos, husband of Antiope and father to the Pierides, nine daughters who wanted to surpass the Muses in the arts. So, they challenged the goddesses into a contest, during which the Muses won. To punish them for their insolence, the Pierides were transformed into nine birds.
See Also: Pierides, Muses