Sauron is the powerful evil being who rules Mordor in J.R.R. Tolkien’s The Lord of the Rings.
Sauron is a Maia, a spiritual being who served the Vala Morgoth in the earlier history of Tolkien’s mythology. After Morgoth’s defeat, Sauron became the central enemy of the Second and Third Ages. He established himself in Mordor and sought to control the peoples of Middle-earth through the One Ring.
Although Sauron is commonly imagined as a dark-armoured figure, Tolkien’s narrative emphasizes his power, will, and influence more than a sustained physical appearance. By the time of the main story, he is represented visually by the Eye in many adaptations, while the book presents his presence through his realm, servants, and searching power.
Sauron and Morgoth are not the same character. Morgoth is the earlier and greater rebel power; Sauron is his most important surviving servant and later becomes the chief antagonist of The Lord of the Rings.