Apotropaic magic (from Greek apotrepein, to ward off : apo-, away + trepein, to turn) is a type of magic intended to "turn away" harm or evil influences, as in deflecting misfortune or averting the evil eye. "Apotropaic" observances may also be practiced out of vague superstition or out of tradition, as in good luck charm (perhaps some token on a charm bracelet), amulets, or gestures like fingers crossed or knocking on wood. The Greeks made offerings to the Averting Gods, (Ἀποτρόπαιοι θεοί: Apotropaioi Theoi), chthonic deities and heroes who grant safety and deflect evil.

Among the Ancient Greeks the most widely-used image intended to avert evil was that of the Gorgon, the head of which now may be called the Gorgoneion, which features wild eyes, fangs, and protruding tongue. The full figure of the Gorgon holds the apex of the oldest remaining Greek temple where she is flanked by two lionesses. The Gorgon head was mounted on the aegis and shield of Athena.

Eyes were often painted to ward off the evil eye. An exaggerated apotropaic eye was painted on Greek drinking vessels in the 6th century BC to ward off evil spirits while drinking.Fishing boats in some parts of the Mediterranean region still have stylised eyes painted on the bows. A Turkish budget airline has adopted the symbol (known as Nazar boncuğu or Nazar bonjuk) as a motif for the vertical stabilizer of its aeroplanes. The Yiddish expression, "Kain ein horeh" (קיין עין הרע) is apotropaic in nature, and literally translates to "no evil eye," somewhat equivalent to the expression, "Knock on wood."