Twenty Rings of Power are named in J.R.R. Tolkien’s legendarium.
The total comes from the famous division described in The Lord of the Rings: three Rings for the Elves, seven for the Dwarves, and nine for mortal Men. Sauron secretly made the One Ring to control the others, producing a total of twenty Rings of Power.
The three Elven Rings are Narya, Nenya and Vilya. The seven Dwarf-rings were associated with the seven houses of the Dwarves, although their individual names are not all given in Tolkien’s main narratives. The nine Rings given to Men ultimately enslaved their bearers as the Nazgûl.
The One Ring is counted in the total, even though it is distinct from the nineteen distributed Rings. Readers sometimes answer nineteen by counting only the Rings made for Elves, Dwarves and Men, or nine by counting only the human Rings. The canonical total includes all three groups plus Sauron’s One Ring.