Dystopian Enforcers Gone Native

I recently watched Repo Men (2010) (my review: meh), a story in which the main character starts out as an enforcer for some bad powerful men, later becomes a target of his fellow enforcers, has a change of heart and begins defending other rebels and dissidents. Seems like one of those fairly archetypal plots, so I tried to think of an appropriate label and began to obsessively catalog how many others could fit this category. (Some of them have a change of heart first that turns them into a dissident, others are more or less unfairly targeted and only have a change of heart because it's happening to them for a change.) Here's what I came up with so far:

Dystopian Enforcers Gone Native
Repo Men (2010)
Avatar (2009)
A Scanner Darkly (2006)
Equilibrium (2002)
The Bourne Identity (2002) (other betrayed spies I'm forgetting?)
Robocop (1987) ?
Blade Runner (1982)
Logan's Run (1976)
Zardoz (1974)
Fahrenheit 451 (1966)


Robocop starts off fighting bad guys, but turns against OCP when he discovers they've gone bad. He's not as much of a jerk at the beginning as the Firemen or Sandmen or Repo Men. He doesn't have a change of heart and doesn't join or start defending street thugs.

The Bourne franchise doesn't fit the usual picture of a dystopia, but that's just because we don't recognize how much of a dystopia we currently live in. Political assassinations and functioning democracy don't mix, yo.

THX 1138 - Not an enforcer
Dances with Wolves - Gone native, but neither dystopian nor an enforcer
Heart of Darkness/Apocalypse Now - Past Enforcers Gone Native

Any others you can think of?

Update:
The Postman
Running Man
District 9
Dune (not dystopian?)
Minority Report
Sleep Dealer
Source Code
Universal Soldier
Fantastic Four #48-50 (1966): the Silver Surfer betrays Galactus and sides with Earth.