In Greek mythology, Zeus’s legendary protective weapon was called the aegis.
The aegis is described in ancient sources as a divine protective covering or shield associated primarily with Zeus. It could produce terror in battle, and its appearance was sometimes linked with the fearsome face of the Gorgon Medusa. Athena also commonly carries or wears the aegis in artistic and literary traditions.
The exact nature of the aegis varies between sources. It may appear as a shield, a breastplate, or a goatskin cloak, so it is not always equivalent to an ordinary metal shield. The name is connected with the Greek word for goat, and some traditions associate it with the goat Amalthea.
The aegis should not be confused with Zeus’s thunderbolt, which was his principal offensive weapon. In modern English, “under the aegis of” means under the protection or sponsorship of someone powerful.