One Ring to control them all, one Ring to find them all, one Ring to bring them all together and bond them in the darkness.
The Elven-smiths created the Rings of Power in ancient times, and Sauron, the Dark Lord, constructed the One Ring, infusing it with his own power so that he could rule over all others. But the One Ring was snatched from him, and despite searching Middle-earth for it, he was unable to find it. It ended up in the hands of the hobbit Bilbo Baggins after many aeons.