XPN-20A

XPN-20A is a synth within the Institute in Fallout 4.

Background
XPN-20A 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.

Appearances
XPN-20A appears in Fallout 4 and Fallout Shelter Online.

Bugs
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.