The Chosen from 7th Legion. (I would have a spoiler warning here, but everything there is to know about the story comes from the intro cinematic and the instruction manual. Seriously.) The story of 7th Legion is that the world became overpopulated, and so the government decided to evacuate people from the planet in order to escape the ensuing famines and plagues, and come back when the planet recovered. However, only the smart, powerful, and rich were chosen. Everyone else was left to die.
The people left behind got pretty pissed and decided that they wanted to get revenge against the Chosen when they got back.
In that game, every time you beat a mission, you see a short cinematic scene that has no story development whatsoever. If you beat a Chosen (Red Guys) mission, then you see some Chosen units brutally killing some 7th Legion (Blue Guys) units and vice versa.
But what makes the Chosen such horrible bastards is that they're pretty much Nazis. They're not just satisfied with wiping out the 7th Legion. They want to kill them in the most brutal ways possible, and even then they're not satisfied. They also have to kill random animals for shits and giggles. Even their symbol looks somewhat like a swastika. In one 7th Legion mission ending, a Chosen soldier sees a lizard, and then for no reason at all, he starts stabbing it to death with his bayonet. Then a 7th Legion mech steps on him and the cinematic ends.
One Chosen ending shows a 7th Legion guy admiring a random bird while some peaceful music plays, then he gets run over by 3 Chosen tanks, and the camera focuses on his upper torso as he lay screaming and dying. Another one shows a 7th Legion getting shot while taking a piss.
The 7th Legion's last mission ending shows a row of Chosen soldiers bound and on their knees. A 7th Legion soldier shoots them all in the head. On the other hand, in the Chosen ending, their positions are switched, and the Chosen decide that headshots aren't brutal enough, so they go with running them over with tanks.
