Sauron is the maker of the One Ring in J.R.R. Tolkien’s legendarium.
Sauron forged 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 as the main vessel for a large part of his power. This connection explains why destroying the Ring is essential to defeating him.
Sauron was originally a Maia named Mairon and served the Vala Aulë before becoming associated with Morgoth. After Morgoth’s defeat, Sauron continued his own campaign to dominate the peoples of Middle-earth. He used deception as well as force, including the fair appearance of Annatar when influencing the Elves who made the Rings.
Celebrimbor and the Elves forged the other Rings, but Sauron alone made the One Ring. That distinction is a common source of mistaken answers to this question.