Sauron is the primary Dark Lord in J.R.R. Tolkien’s The Lord of the Rings. He seeks the One Ring because it would restore and greatly increase his power.
Sauron was originally a Maia, a powerful spiritual being in Tolkien’s mythology. He served Morgoth, the first Dark Lord, during the First Age. After Morgoth’s defeat, Sauron became the principal enemy of the later ages.
Sauron helped create the Rings of Power and secretly forged the One Ring in Mount Doom. The Ring contained much of his own power, which made its destruction necessary for his final defeat.
Sauron is sometimes confused with Saruman, who is a wizard and later becomes his ally, or with Morgoth, who predates him as the supreme evil power. Sauron’s physical form changes across Tolkien’s history.