The aegis (/ˈiːdʒɪs/ EE-jis; Ancient Greek: αἰγίς aigís), as stated in the Iliad, is a device carried by Athena and Zeus, variously interpreted as an animal skin or a shield and sometimes featuring the head of a Gorgon. There may be a connection with a deity named Aex or Aix, a daughter of Helios and a nurse of Zeus or alternatively a mistress of Zeus (Hyginus, Astronomica 2. 13). The aegis of Athena is referred to in several places in The Iliad. "It produced a sound as from a myriad roaring dragons (Iliad, 4.17) and was borne by Athena in battle … and among them went bright-eyed Athene, holding the precious aegis which is ageless and immortal: a hundred tassels of pure gold hang fluttering from it, tight-woven each of them, and each the worth of a hundred oxen."
The modern concept of doing something "under someone's aegis" means doing something under the protection of a powerful, knowledgeable, or benevolent source. The word aegis is identified with protection by a strong force with its roots in Greek mythology and adopted by the Romans; there are parallels in Norse mythology and in Egyptian mythology as well, where the Greek word aegis is applied by extension.