- "The Eye of Sauron the Terrible few could endure."
- —The Silmarillion
The Eye of Sauron was a symbol adopted by the Dark Lord during the Second Age and the Third Age. It was said that few could endure the eye's terrible gaze. The Eye was used on armor and banners of Mordor as a symbol of Sauron's quasi-omnipotence, and was adopted as something of an insignia by Sauron's forces in general.
In the Lord of the Rings novels, the Eye is simply a metaphor for Sauron's overwhelming spiritual presence and his vast farsight, as it is implied that Sauron has a physical body during the events of the novels. The only instance of the Eye manifesting in a somewhat physical sense was when Frodo looked into the The Mirror of Galadriel and saw the Eye searching for the One Ring.
In Peter Jackson's film series however, the Eye is literally a gigantic eyeball composed of energy that sits atop Barad-dûr. In the films, Sauron's corporeal form is in fact the Eye, and he lacks a humanoid form.
- Sauron Eye live animation following mouse