The reason for this is that, instead of becoming all-powerful, Gollum is what Smeagol would become after being corrupted by the One Ring for far too long. When it comes time for some kind of ...

In the movies, the wizard says he "searched everywhere for the creature Gollum," but "the Dark Lord found him first." In the books, Aragorn reveals that he did manage to capture Smeagol ("he bit me ...