Nightkin

The Nightkin are an elite warrior caste in the Master's super mutant army. They can be found in the upper levels of the Cathedral, as well as inside the Mariposa Military Base, including the nearby cells surrounding it in the form of random patrol encounters.

They are superior to other supermutants in skill, equipment and weaponry. Many of the Nightkin are equipped with cloaking devices, the Stealth Boys. The only gaming effect of this is to give them a slight ethereal look, as it does not affect the PC's chance of hitting them.

After the Master's fall, many surviving unity super mutants had become a chaotic wasteland wandering force, set on destroy everything it encountered. During the time of Fallout 2, some of the super mutant 'gangs' included the former (or so called) nightkins. However, they no longer used Stealth Boys. In Fallout: New Vegas, some of the nightkins will reappear, still using the Stealth Boys.

A part of super mutant army remained intact after the death of Master. The group of surviving mutants was assembled into a new faction, led by Attis. Many years after their regrouping, these mutants captured the Secret Vault in order to use the FEV reserves stored in it. Attis's goal was to continue the Master's plan. His army had an elite unit of Nightkins, much improved in skill, and equipped with high-tec suits to enhance their abilities. These suits probably originated from, or were made in Vault-Tec facilities in the region.

Canon games
The Nightkin appear in Fallout in the Cathedral and the Mariposa Military Base, and in Fallout 2 as a hostile encounter on the World map.

In Fallout 3, the word 'Nightkin' occasionally appears in the password list when hacking a terminal. As for Fallout: New Vegas, they will make an appearance as a bonafide enemy.

Non-canon games
Nighkin also appear in Fallout: Brotherhood of Steel.

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