The Dec. 17 debut of “The Hobbit: The Battle of the Five Armies” marks both an end and a beginning for Peter Jackson.

It represents the culmination of his 16-year, six-film J.R.R. Tolkien marathon — an outsized success in duration, execution, visual-effects wizardry and overall popularity. No director in history has maintained tighter control over the creative direction of a global film franchise, which so far has amassed close to $5 billion in ticket sales alone.

But after bringing his Mi