The One Ring, as it is featured in the Peter Jackson's live-action movies. It also appears in the Non-Disney Villains Tournament - Round 6, and in Disney vs. Non-Disney Villains War continuity.
The One Ring is the key element item of the Tolkien universe, The Lord of the Rings, serving as the basis of the whole franchise. A ring of incredible and immense dark power, forged by the Dark Lord himself, Sauron, the One Ring has the potential to corrupt the user, who would currently possess the ring, forcing the user to fall before the Dark Lord's powers.
It also appears in the villains tournaments context, usually featured under the possession of strong inviduals, including Rumpelstiltskin in Disney vs. Non-Disney Villains, Eris and Rameses in the Non-Disney Villains Tournament, and formely Taran in Heroes vs. Villains, before giving the ring to Frodo Baggins' possession.
Disney Vs Non-Disney Villains War
Pre-War:
Disney Vs Non-Disney Villains War - Part Three
Non-Disney Villains Tournament
Archive Footage of Moses' Ring, used to represent the One-Ring's footage, under the possession of Rameses. This version appears in the majority of the Non-Disney Villains Tournament, and in some cameo appearances of Heroes vs. Villains.
Heroes Vs Villains War
The One Ring, as it is featured in the Ralph Bakshi's version of the Fellowship of the Ring. This version also appears in Heroes vs. Villains.