Vaas Montenegro quickly became a breakout star for Far Cry 3 and set a pattern for the series emphasizing charismatic antagonists, but he became especially well-known for one particular scene. After Brody is captured by the pirates, Vaas confronts him with the famous monologue: "Did I ever tell you what the true definition of insanity is? Insanity is doing the same f**ing thing, over and over again, and expecting s**it to change. That is crazy."
Vaas is right. The "true definition of insanity" can be seen in several forms throughout Far Cry 3, but it's also grown into a staple of the series. Throughout the games, people run into the problem of doing the same thing over and over again trying to bring change. Far Cry is structured around the theme of violence as an unbreakable cycle. Every game sees an effort to bring change through violence only to end in more violence and the world in a worse state than it started. The biggest victory the player can have is often just to get out of the mess in one piece. This idea regularly pops up throughout the franchise in various forms and is embodied by several different characters. Far Cry fans keep finding people who do the same thing over and over again hoping for change, sometimes to the point where it becomes their undoing.
5 Jason Brody
Insanity was a core theme of Far Cry 3, but a big part of the game was Jason Brody's descent into the Rakyat warrior lifestyle. Over time, he became good at one thing: killing. Jason starts with a simple goal: finding his friends and getting off the island. But the more pirates he kills, the more he loses sight of what he's fighting for. While he does manage to free most of them from the pirates (save for one who was killed and another who escaped on her own), this does very little to change their situation as they just end up hiding in the cave under Dr. Earnhardt's house.
Jason's violence never really got them any closer to finding a way off, either. In fact, it actually starts to get worse when he becomes more obsessed with killing Hoyt, and Citra's continued brainwashing doesn't help. Unlike many on this list, Brody actually gets a choice to either embrace true insanity or resist it when Citra tries to make him kill his friends. Fittingly, doing something different by releasing them allows him to finally accomplish his initial goals while choosing to do more killing leads to an ending where he is himself murdered.
4 John Seed
The younger brother of Eden's Gate founder Joseph Seed is consistently portrayed as an unhinged maniac obsessed with what he calls "The Power of Yes" and a need to extract the supposed sins of everyone not in the cult, by any means necessary. As he himself claims, atonement can only be accomplished through pain, and he's developed a habit of torturing and forcibly tattooing people until they "Say Yes." This becomes a problem when it comes to the deputy, who consistently manages to resist John's efforts.
He tries both torturing the deputy and trying to force their compliance by threatening their allies. Neither works. John's sessions keep ending with the deputy either being rescued or managing to escape because of his carelessness. And yet, he keeps trying again and again to force the word "yes" out of the Deputy. Ironically, it ends up being his undoing. When he finally gets the response he wants, it turns out the Deputy has one more trick up their sleeve that turns the situation around resulting in a chase that ends with him dead.
3 Pagan Min
Pagan Min was the charismatic but ruthless dictator of Kyrat, known for his extreme responses to the smallest things. His habit of regularly jumping straight to violence and wondering why he has so much difficulty maintaining order would be a great example of true insanity, but even more so is his one soft spot. For a man who is otherwise a narcissistic monster, Pagan did seem to love his wife Ishwari and, by extension, her son Ajay; enough that he was willing to hand over his country to the latter.
The only problem is Ajay is given a lot of good reasons to dislike Pagan Min and gets roped into the Golden Path. Despite getting his butt kicked by Ajay again and again, Pagan keeps trying to win him over. He also has a habit of cheerfully telling Ajay anecdotes about people whose lives he ruined, as though that wouldn't give Ajay even more reasons to dislike him. He even goes as far as to set up his own adopted daughter Yuma to be killed by Ajay. Depending on the player's choice, Pagan's refusal to give up on Ajay can either be his undoing (due to Ajay finally killing him), or it can pay off when he finally accomplishes his intended goal.
2 Willis Huntley
Willis Huntley is a CIA agent and a recurring character throughout the Far Cry series. He first appeared in Far Cry3 but made further appearances in 4 and 5, as well as a cameo in 6. While working on the Rook Islands in 3, he claims he doesn't go into the field because he's afraid of losing his sanity in the same way as many others. Despite this, there is a pretty consistent pattern he follows in each appearance.
His standard routine is to show up, make the protagonist do his job for him, then abandon them as soon as they're no longer needed, usually leaving them at the mercy of the game's antagonists. He sends Jason on a potential suicide mission in Far Cry3, sells out Ajay to Yuma in Far Cry4, and abandons the Junior deputy after promising to deal with Eden's Gate in Far Cry5. Supposedly, he's a patriot fighting the good fight for the United States but there's never really any evidence of his actions actually making any meaningful difference. Maybe the Rook Islands affected his sanity after all.
1 Ull
Far Cry Primal made the interesting decision to move the series into the Stone Age, but it also showed that even early cavemen could not escape "true insanity." This is most evident with the Udam, a Neanderthal tribe led by a warrior named Ull. Of the two antagonists, Ull is definitely the more sympathetic one as he really just wants to save his people from the "skull-fire" disease that's plaguing them. The only problem is his inability to realize the only "treatment" he knows is actually causing the disease.
The Udam have a history of eating their enemies, and a deep-rooted belief that eating flesh from other tribes gives them strength. Ull's strategy for saving the Udam from the skull-fire is therefore to kill and eat members of the Wenja tribe, only they can't understand that eating human meat comes with health risks. In a particularly tragic example of "true insanity," Ull is put in a positive feedback loop. The skull-fire disease keeps appearing, so the Udam keep eating more Wenja which only leads to more skull-fire. The inability to escape this loop most likely doomed the Udam to extinction.