Who gets his power from a ring?
The superhero who gets his power from a ring is Green Lantern.
The Green Lantern Corps is an intergalactic police force that uses power rings to create constructs of solid green energy, which they use to fight crime and protect the universe.
Each ring is powered by the wearer's willpower, and can be used to perform a wide variety of tasks, from creating force fields to flying through space.
There have been several different Green Lanterns over the years, including Hal Jordan, John Stewart, and Kyle Rayner, among others.