The One Ring is often reduced to a familiar idea: power corrupts. But Tolkien’s treatment of the Ring is considerably more complex. This investigation examines the Ring through Tolkien’s fiction, letters, compositional history, literary scholarship, theology, philosophy, psychology, philology, and comparative myth. Beginning with Frodo, Boromir, Gollum, and Sauron, the investigation expands to Gandalf, Galadriel, Sam, Bilbo, Faramir, Saruman, Denethor, the Nazgûl, the Elven Rings, the palantíri, and Tolkien’s wider moral universe. The resulting picture is not simply a warning against power. The Ring represents a more particular danger: the temptation to make one’s will effective by overcoming the freedom, resistance, uncertainty, and independence of the world and of other persons. Across the investigation, domination, possessiveness, moral rationalization, dependency, finitude, mercy, relinquishment, and redemption emerge as interconnected themes. The deepest question becomes not whether power is inherently evil, but how finite beings can act, lead, create, protect, and pursue genuine goods without crossing the boundary between responsible agency and mastery.