J.R.R. Tolkien identifies Sauron as the maker 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 to dominate their bearers. Because he placed much of his own power into the Ring, its destruction would permanently defeat him, although possessing it also made him dangerous.
Sauron originally served Morgoth, the chief evil power of Tolkien’s earlier history. After Morgoth’s defeat, Sauron continued his efforts to rule Middle-earth. He appeared in different forms and names, including Annatar, “Lord of Gifts,” while deceiving the Elves involved in the making of the Rings.
Celebrimbor helped create the Elven Rings but was not the maker of the One Ring. Morgoth is Sauron’s former master, and Saruman is a later corrupted wizard. These connections explain why the names are sometimes mixed up in summaries of Tolkien’s mythology.