Raiders

Raiders are common enemies in the Fallout video game series.

Summary
They are survivors of the Great War that have turned to random murder and pillaging in order to survive in the wasteland. They are generally completely barbaric and devoid of redeeming qualities, killing virtually anyone outside of their fellow raiders, especially after living like savages in the chaotic post-war world for extended amounts of time. Because of their primitive scavenger nature, raiders are usually less organized and well equipped than more civilized post-war groups like the NCR and Brotherhood of Steel.

Various Raider gangs are present all throughout the ruins of America and appear in all Fallout games. Even in places where civilization and order have started to rebuild, raiders still remain a constant nuisance and always will be, much like common street thugs in today's world. Some raider groups are stronger and more civilized/less savage than others.

Raiders are most prominent in Fallout 3. The raiders of the Capital Wasteland are among the most depraved of all and are found everywhere throughout the game world as one of the main enemy types. They are all labeled simply as "Raider".

In Fallout: New Vegas, raiders are much weaker and less common than in Fallout 3 thanks to the law enforcement of the NCR, and now organized into different gangs unlike in the previous installment. One notable gang encountered early in the game are the Powder Gangers, who are escaped NCR convicts that like to use explosives. The "Great Khans", a new incarnation of the Khans group originally featured in the original Fallout, have become less raider-like over the years and are now a tribe of savage warriors rather than complete murderous lunatics. But the most dangerous and evil raiders in New Vegas are the Fiends, a bunch of insane drug addicts who terrorize the ruins near the New Vegas city complex.

Initiation
Methods of initiations are different depending on Raiders, but they are all brutal and dangerous.

Khans and Great Khans: beating up initiates for an hour. If the initiate does not manage to cry out and survives, then he/she is passed. Females are to undergo the same initiation treatment and are granted no special treatment.

Forged: those who failed to pass the initiation are tossed down to Shaft Furnace.

Raiders from Eastern region: beating up initiates by 3~4 members. If initiates successfully endure beatings withing certain amount of time then he/she is passed. If they fail and die, their bodies will be hanged on the ceilings.

Trivia

 * In Fallout 4, for all their barbaric and savage nature, a handful of Raiders do show prides and sliver of their humanity in private: This was shown when a Raider sits at the grave of a fallen female Raider, or keep on muttering "Not your fault... No other way... I had to..."