Sauron is the evil power who forged the One Ring in J.R.R. Tolkien’s legendarium.
Sauron created the One Ring in the fires of Mount Doom during the Second Age. He designed it to control the other Rings of Power and used it to dominate the peoples of Middle-earth. Because much of his power was bound into the Ring, destroying it was essential to defeating him permanently.
Sauron originally served Morgoth, the first Dark Lord, but later became the principal enemy of The Lord of the Rings. He could take fair forms in earlier periods, including the name Annatar, before openly returning as a tyrant. By the end of the Third Age, he appears mainly as a disembodied, searching will associated with the Eye.
Morgoth is a common confusion because he was Sauron’s former master and an even earlier cosmic enemy. Saruman is a powerful wizard corrupted by Sauron’s influence, while the Witch-king is the chief of the Nazgûl.