We've got:

Metal Gear Ray (Modo): A tank with an overbloated budget, typical of the MIC, that gets taken down super easily

Blade Wolf: Actually not that bad of a person, but still another over-budgeted war machine.

Mistral: French Foreign Legion member who feels compelled to fight, and acts cruelly to poor Blade Wolf,

Khamsin: The Troopiest Troop who ever Trooped, thinks he's fighting for freedom of... Abkhazia?

Monsoon: Complete psychopath, thinks all humans should act like he does, had his vision informed by the Khmer Rouge, also likes memes.

Sundowner: War Profiteer, Warmonger, PMC CEO, literally destabilizes countries for profit

Jetstream Sam: Worships the feudal Samurai, so probably is also a reactionary. Otherwise one of the least bad bosses.

Metal Gear EXCELCIUS: Even bigger tank, even more useless, even bigger budget

Senator Armstrong: Social Darwinist, claims he wants to start a bigger War on Terror, but actually wants to make Amerikkka somehow an even worse place to live. Plus, he's an Amerikkkan senator.

In the end, though, you kill them, so the game's cool.