Well, I know trolls, elves, goblins, orcs, wraiths, wargs, wizards, dragons and eagles at least were all existing notions. Some of them he popularized (e.g. "or

Well, I know trolls, elves, goblins, orcs, wraiths, wargs, wizards, dragons and eagles at least were all existing notions. Some of them he popularized (e.g. "orc" and "warg" were both lost to modern usage before Tolkien brought them into currency), but he didn't invent them. I know "balrog" and "hobbit" were original, but I think most of it was a synthesis of existing mythology. Can you come up with many more original species?