Alastor

Alastor, an epithet of the Greek god Zeus, according to Hesychius of Alexandria and the Etymologicum Magnum, which described him as the avenger of evil deeds, specifically familial bloodshed. As the personification of a curse, it was also a sidekick of the Erinyes. The name is also used, especially by the tragic writers, to designate any deity or demon who avenges wrongs committed by men. In Euripides' play Electra, Orestes questions an oracle who calls upon him to kill his mother, and wonders if the oracle was not from Apollo, but some malicious alastor. There was an altar to Zeus Alastor just outside the city walls of Thasos.