Sauron was the first bearer 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 created it to control the other Rings of Power and to extend his influence over their bearers. Because much of his power was invested in the Ring, possessing it was central to his strength and authority.
The Ring was cut from Sauron’s hand by Isildur during the War of the Last Alliance. Isildur refused to destroy it, beginning a long sequence of transfers that eventually brought it to Déagol, Sméagol, Bilbo, and Frodo. These later bearers are therefore not the Ring’s first owner.
Sauron’s connection with the Ring also explains why its destruction is required to defeat him permanently. The Ring is not merely a powerful piece of jewelry; it is the chief vessel of the Dark Lord’s power.