In J.R.R. Tolkien’s mythology, Sauron is the creator of the One Ring.
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 a vessel for much of his own power. The Ring’s destruction therefore becomes essential to defeating him permanently.
Sauron originally served Morgoth, the first Dark Lord, but rose to become the principal enemy of the Second and Third Ages. His influence reaches across The Lord of the Rings even though he never appears in a normal physical form during the main narrative.
Celebrimbor helped create the Elven Rings and was deceived by Sauron, while Saruman is a later servant of Sauron. Morgoth is Sauron’s former master and a different character. That distinction matters because the two villains belong to different historical eras in Tolkien’s legendarium.