The aegis or aigis (Ancient Greek: αἰγίς; English pronunciation: /ˈiːdʒɪs/), as stated in the Iliad, is carried by Athena and Zeus, but its nature is uncertain. It had been interpreted as an animal skin or a shield, sometimes bearing 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.
Virgil imagines the Cyclopes in Hephaestus' forge, who "busily burnished the aegis Athena wears in her angry moods—a fearsome thing with a surface of gold like scaly snake-skin, and the linked serpents and the Gorgon herself upon the goddess's breast—a severed head rolling its eyes", furnished with golden tassels and bearing the Gorgoneion (Medusa's head) in the central boss. Some of the Attic vase-painters retained an archaic tradition that the tassels had originally been serpents in their representations of the aegis. When the Olympian deities overtook the older deities of Greece and she was born of Metis (inside Zeus who had swallowed the goddess) and "re-born" through the head of Zeus fully clothed, Athena already wore her typical garments.