Sauron is the evil being who forged the One Ring in J.R.R. Tolkien’s mythology. He created it in the fires of Mount Doom to dominate the other Rings of Power and extend his control over their wearers.
Sauron was originally a Maia, a powerful spirit who served the Vala Aulë before becoming associated with the fallen Vala Melkor, later called Morgoth. In the Second Age, Sauron helped create the Rings of Power while concealing his identity as Annatar, the Lord of Gifts.
Morgoth is Sauron’s former master and a greater primordial enemy, not the maker of the One Ring. Saruman is a corrupted wizard in The Lord of the Rings, and the Witch-king is Sauron’s chief servant. Sauron’s power remains tied to the Ring even after his physical form is destroyed.