"Those forced out of their colonies and enclaves who manage to survive become the progenitors of the raider clans, learning the secrets of how to treat mutant flesh to make it edible, resorting to cannibalism so often that many developed a taste for 'long pig', and domesticating and propagating a stew of bio-organisms that can purify and reclaim tainted water into something potable. The resulting brew tastes unpleasant but is rich in micro-nutrients and even has some simple protein chains." -Wastelander
Raiders are humans who have banded together to raid people, ironicly enough you do the raiding and they don't even raid you (except the ones that do). All raiders are hostile and some are required to be killed to continue the story. Notable Raider gangs include Axle's Raiders, The Motorsykos, The Sale'oarz, the Road Raiders, the Skaard, The Deathridaz, The Freebooterz, and The Bludskull Gang.
You must fight Raiders in mutiple chapters, but in chapter 14 they decide to declare war on you and your allies. They destroy your (brainwashed) MCP Compounds, They attack your colony, and lay waste to your allies...so what do you do? YOU NUKE THEM SO BADLY THEY CAN'T EVEN FIGHT BACK!
For Raider Buildings go here -----> Raider Buildings