Sauron is the ruler of Mordor in J.R.R. Tolkien’s The Lord of the Rings.
Sauron is a Maia, a spiritual being who originally served the Vala Morgoth. After Morgoth’s defeat, Sauron became the chief enemy of the Free Peoples of Middle-earth. He established Mordor as his stronghold and used the land’s volcanic geography to support war and industry.
Sauron forged the One Ring in the fires of Mount Doom, intending to dominate the other Ring-bearers and control the peoples who used the Rings of Power. Because much of his power was bound into the One Ring, its destruction was essential to his final defeat.
Sauron is not the same character as Saruman. Saruman is a wizard and a member of the Istari who becomes his ally. Morgoth, also called Melkor, was Sauron’s former master and the greater evil of Tolkien’s earlier mythology. The Witch-king was Sauron’s most powerful servant among the Nazgûl.