Eye of Sauron
The Eye of Sauron is part of the fictional Middle-earth, a literary universe by J. R. R. Tolkien.In the book The Lord of the Rings, the Eye of Sauron is within the Dark Tower, Barad-dûr. It is described as having flames on its rim. Sauron's Orcs use the sign of the Eye when they roam the Earth.
In Peter Jackson's movies, The Lord of the Rings: The Fellowship of the Ring and The Lord of the Rings: The Two Towers, Jackson envisions Sauron as being a spirit-like being who cannot (yet) take bodily form. Sauron's only physical presence is as a giant disembodied red eye, seen in the second movie as floating above Barad-dûr. The Eye is referred to as having the capability to "see all", although that must be meant as a term of fear and not literally; Sauron is not aware of most events that occur in Middle-earth.
Pippin had a brief and frightening encounter with the Eye, after gazing into the palantír of Orthanc.