The Hunchback of Notre Dame: Judge Claude Frollo wants to destroy the race of gypsies for "inflaming the people's lowest instincts". His fanaticism is bad enough at first when he accidentally kills a gypsy woman for hiding "stolen goods" (which turn out not to be stolen goods at all, but instead, her deformed baby), but at least at that point he had a code of conduct and morality: he's very clearly devout (though in a twisted, totally-missing-the-point way), and on the priest's command takes in Quasimodo and raises him. But add some creepy lust for another gypsy woman and things reeeeeally go downhill. If anything, Frollo is a deconstruction of a Knight Templar. As a Knight Templar, Frollo believes that All Crimes Are Equal, and that the punishment for every single one is death. While the gypsies have committed crimes, they have not done anything to bring this kind of punishment down on them. Frollo even has a family's house set on fire with them in it, even though they do not even know about the gypsies. This causes Phoebus to turn against him, and Frollo to try to kill him in return. He considers the gypsies to be vermin and advocates genocide against them. Frollo demonstrates why a Knight Templar, logically and realistically, would be a horrible person.
The Great Candlestick from The Painting is perfectly fine with the way things are in the painting, which involves forcing some the inhabitants to live outside in the garden and others to basically be hunted for sport. The fact he gets to be in charge of, well, everything might have something to do with it.
The Christians in Agora. Special mention must go to Ammonius, who is this Up to Eleven and to the point of Stupid Evil. The pagans aren't much better, though, doing a Too Dumb to Live move, attempting to avenge "an insult to the gods".
American History X: Derek before he gets out of prison. He thinks he is absolutely right in spouting his racist ideology even when he organizes attacks and horrifying brutalities against minorities. By contrast, the Aryan Brotherhood are presented as Straw Hypocrites. Which is largely the point that the film tries to get across. The reason destructive ideologies like white supremacism can become so powerful is because their adherents believe themselves to be the heroes, not the bad guys.
In Captain America: The First Avenger, HYDRA was a 1940s Stupid Jetpack Hitler organization with designs to Take Over the World. But this changes by the sequel, which is set in the present day. Now led by former HYDRA scientist Arnim Zola (who was supposedly recruited as an Allied researcher following the war), they've secretly backdoored their way into the governments of the world and are using their influence to carefully manipulate the people of the world into believing they're better off having their freedoms denied in exchange for security. Their plan is set to come full circle with the launching of "Project Insight".
Dark Angel: The Ascent: The demoness in the film starts to kill several wicked people during her time on Earth by gutting them and feeding them to her dog.
Played with The Dark Knight, Harvey "Two-Face" Dent who becomes an insane crusader himself after letting his desire for justice get the better of him, right after hearing the bad news from The Joker about Rachel Dawes' death. He is not a full example however as he is more of a mad nihilist who enforces chance to decide who lives and who dies seeing it as the only fair judge and yet still chooses the ones that he blames for everything, rightfully or not.
The government of Libria in Equilibrium suppressed human emotion, as it was believed responsible for causing the human tendency for violence that brought about the war that practically destroyed the world, which meant destroying art, movies, and other things inductive of emotion (including cute little dogs) and terminating "sense offenders" who go without the government mandated drug called Prozium.
In Frailty, Matthew McConaughey's family is commanded by God to destroy demons. One of the kids sees "destroy demons" to mean "kill people". The dramatic irony is that all the people killed are murderers or worse, and the demons are real.
Michael Corleone in The Godfather trilogy takes over the family and explains his ruthless actions as doing what it takes to protect the family. At the beginning of Part 1, when he was just a civilian, he tells Kay a story about his father's ruthlessness and claims that's not him. Near the end of the film, he tells Kay that his father's actions are no different than those of other men in power and calls Kay naive for believing otherwise.
Battra from Godzilla (in the films) was created by the Earth to be its protector. However, while his intentions are in the right place, his actions are another story. There's a reason Mothra had to seal him away.
Holocaust 2000: Robert is attacked by a religious madman who is convinced that he will bring about the end of the world. He kills Robert's wife instead when his son Angel intervenes to swerve the assassin's knife out of the way.
Blaine and his ski patrol friends in Hot Tub Time Machine. They have a legitimate mission of maintaining law and order on the mountain, but they use this and the Red Scare as an excuse to be Jerkasses.
The Paladins in Jumper, led by Samuel L. Jackson. They believe that they are doing God's will by murdering all of the jumpers, as "only God should have that power". Whoever steps outside their narrow-minded standards of the world is dead meat.
Hit Girl and Big Daddy in Kick-Ass fit the bill, despite being protagonists. Hit Girl indiscriminately kills the occupants of an apartment, when some of them are innocent bystanders or not directly criminals.
A literal version in Kingdom of Heaven; the King's brother-in-law and his right-hand man are actual Knights Templar who also fit the trope to a T. When the king dies and the brother-in-law becomes king, it comes to the point of killing the Saracen leader's sister in order to provoke a conflict.
Karl Aker from Kite, as opposed to his equivalent from the anime. He trained, equipped and brainwashed Sawa for the express purpose of destroying the human trafficking ring, including blaming the death of Sawa's parents on the ringleader, the Emir.
In Man of Steel, Zod believes he's ultimately doing what's best for his people. In fact, due to Krypton using Designer Babies to fulfill roles in their society, he cannot help it.
Zod: No matter how violent, how cruel, every action I take is for the greater good of my people.
Non-Stop: Marks starts skirting this trope as he becomes increasingly desperate to find the man behind all of this, who turns out to be an example himself, willing to blow up a plane and kill over 150 people to make a point about how vulnerable American airlines are to terrorist attacks.
The anonymous sniper from Phone Booth is another. His targets are usually unrepentant criminals like murderers, child molesters, and, at one point, a businessman who made off with a collapsed company's profits, leaving his employees and investors to rot. His target in the film, however, isn't any type of criminal, but simply Jerk Ass Stu Shepard, who is having an affair and pretending to be a big shot; not exactly what you would call pure evil. Also, the sniper's methods to get criminals, real or imaginary, to confess, including targeting their loved ones, are quite questionable, to say the least. In the end, Stu confesses to his deeds, and the sniper decides to spare his life and those of his loved ones...though it's hinted that the sniper is going to check up on Stu once in a while to make sure that Stu keeps his promise of not being a douche.
The Jigsaw serial killer in Saw does not consider himself a killer. Oh, sure, he acknowledges that his actions frequently lead to horrible death, but he never pulls the trigger. And he firmly believes that the people who survive his themed deathtraps will overcome their sins and become better (though this never actually works).
In a way, some of the Alliance can be seen as Knights Templar, considering that they killed thirty million people on Miranda while testing a peace-inducing chemical inhalant and the entire justification for them cutting River's brain up was to "make a better world".
Jonathan Doe from Se7en believes that he is punishing the wicked by killing people that go against his belief system. It could be argued, however, that he is at heart a sadistic psychopath who uses religion to justify to himself that people deserve to be brutally punished for being imperfect. And in fact he doesn't even exclude himself from this!
In the Cold War political thriller Seven Days in May, General James Mattoon Scott is secretly staging a coup against the President of the United States because he disagrees with the President's efforts to set up a disarmament treaty with the Soviets. Several chilling Breaking Speeches, followed by some equally impressive Kirk Summations, follow toward the end.
General Scott: James Mattoon Scott, as you put it, hasn't the slightest interest in his own glorification. But he does have an abiding interest in the survival of this country.
President Lyman: Then, by God, run for office. You have such a fervent, passionate, evangelical faith in this country - why in the name of God don't you have any faith in the system of government you're so hell-bent to protect?
Transformers: Dark of the Moon: Sentinel Prime, former commander of the Autobots, is revealed to be this. Originally Optimus's mentor and father-figure, Sentinel had been corrupted by eons of war. Convinced that Cybertron's survival was more important than loyalty to his men, Sentinel struck a deal with Megatron to find another world whose resources could be used to replenish Cybertron. Finding himself on Earth in present day, Sentinel turns on his former allies and joins Megatron to begin making plans to use Earth's resources (in particular, the six billion or so fleshlings they can turn into a Slave Race). Sentinel's Knight Templar status is also revealed to be influenced by his god complex; remembering how the Cybertronians, particularly the Primes, once lived like gods, he is immediately disgusted by how Earth's leaders treat the Autobots as simple machines.
TRON: Legacy: Clu, in his pursuit for the perfect system, eradicates every single thing he believes to be an imperfection...including the ISOs, which his user believes to be a miracle, and could have very well changed the system and the real world for the better had it not been for Clu's fanaticism.
The Star Chamber is about a young judge becoming frustrated by having to let obviously guilty murderers Off on a Technicality, and joinging a group of his fellow judges who feel the same way. They hold a secret court which "tries" these accused murderers, convicts them, and sentences them to death, with a hitman carrying it out.
In Star Trek VI: The Undiscovered Country, several Starfleet and Klingon officers conspired to preserve their respective ways of life by sparking a war between the Empire and the Federation. It's often pointed out that in conspiring to prevent Federation and Klingons from ever working together for the common good, the conspirators ironically proved that the Federation and the Klingons can work together for what they perceived to be the common good.
Mace Windu of the Prequel Trilogy is a surprisingly subtle version of this. While Mace lacks the self-righteousness that many other counterparts have, he believes that the Republic is an unquestionable utopia, and that peace must be upheld there even if it means breaking the Jedi Code. Palpatine uses his nature against him; Mace's militant approach was the final straw to push Anakin over to the dark side.
Grand Moff Tarkin from A New Hope is also this. He prefers extremely ruthless measures such as the destruction of Alderaan, as he believes that it will help spread order in the galaxy through fear.
Anakin Skywalker/Darth Vader. In the prequels, before he turned to the Dark Side, Anakin was showing shades of this, being disappointed with how ineffectual the Old Republic had grown, believing a more authoritarian approach was necessary to resolve problems. Upon turning to the Dark Side in Revenge of the Sith, he is led to think that destroying the Jedi Order is necessary to bring peace to the Empire.
In the 1983 Italian schlock Post-Apocalyptic film Warriors of the Wastelands, the main villains call themselves Templars, and are dead set on destroying all literature (since they feel that books led to World War III) and anyone who isn't them.
Subverted in The Wicker Man (1973), where Sgt. Howie is introduced as a religiously intolerant, uptight Jerk Ass. However, his faith and sense of duty are presented in a more and more admirable light as the film progresses, and he's far less infuriatingly fanatical than the townsfolk.