In Greek mythology, Penthilus was the son — illegitimate or legitimate — of half-siblings Orestes and Erigone. He was the mythical ancestor of the Penthilidae, an ancient dynasty of kings on Lesbos, and in some accounts led Aeolian colonists to Thrace or founded a city on Lesbos.
Adapted from Wikipedia, "Penthilus (son of Orestes)" · CC BY-SA 4.0
I.Family
Penthilus' grandmother was Clytemnestra; his maternal and paternal grandfathers were Aegisthus and Agamemnon respectively. He fathered two sons, Echelatus (also Echelas or Archelaüs) and Damasias (Damasius), father of Agorius.
Erigone is said either to have hanged herself or to have married Orestes after Hermione's death. In some accounts Penthilus ruled the Argives with his half-brother Tisamenus.
II.Mythology
One story says that as a child Penthilus was torn apart and devoured by wolves in the Taygetus mountains near Sparta, and that his father established a festival of mourning, the Penthilia, in his honour.
According to Pausanias, Penthilus grew up and founded a city either on Lesbos or in Thrace. He was the mythical ancestor of the Penthilidae of Lesbos. His son Echelas was the father of Gras, founder of Aeolis between Ionia and Mysia; in other accounts Penthilus himself led a colony of Aeolians to Thrace.