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XPN-20A is a synth living in the Commonwealth in 2287.


He is a hostile synth encountered in the Institute's reactor room during the quest The Nuclear Option with any faction. XPN-20A, along with A-2018 and Z4K-97B, will serve as the game's final boss during all endings other than the Institute ending.

Interactions with the player characterEdit

Interactions overviewEdit

General Services Quests
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The Nuclear Option


Apparel Weapon Other items On death
Synth uniform


XPN-20A seems to posses unique carbon fiber variants of standard synth armor. However these are unobtainable, given that the unique armor is actually part of its model. One can pacify XPN-20A with the Wasteland Whisperer perk, however equipping new armor to the character will just layer it over the unique armor. The unique black armor will not appear in the character's inventory, regardless of acquisition techniques.


XPN-20A appears only in Fallout 4.


xboxoneIcon xboxone ps4Icon ps4 pcIcon pc Unlike Z4K-97B and A-2018, XPN-20A does not spawn in the reactor room, but next to the elevator at the center of the main floor, before going into the Advanced Systems wing. Thus making the last fight a bit easier.[verified]

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