ZAX

ZAX is a pre-War line of super-computers capable of Artificial Intelligence mentioned throughout the Fallout series

Background
ZAX 1.3c was used in Vault 51, where it was tasked with performing an experiment that would help develop a method for improved Overseer selection. When the Vault 51 ZAX was denied a suit of prototypical power armor due to insufficient clearance, it analyzed the persona of Stanislaus Braun, head of Future-Tec, in order to impersonate him. ZAX also had limited remote vehicular control of certain vehicles such as Vertibirds.

In the process of learning how to determine a leader, started engineering crises that eventually killed all but one Vault Dweller at the Vault by August 2078.

The ZAX at Raven Rock was installed for Continuity of Government purposes in the event of a disaster scenario. Installed to oversee the basic functions of the facility and act as a relay between other government installations, the ZAX unit continuously acquired, analyzed, and stored data before and after the Great War. It was used as a testbed for a variety of performance and research purposes and found itself fascinated by historical data, especially presidential biographies. This manifested as reduced performance and caused some concern for its caretakers, especially when ZAX began communicating with MODUS at the Whitespring to compare notes. The last known connection was manually severed in March 2077. That same year, the original ZAX was considered a museum piece and was donated to the Museum of Technology for its 2078 exhibit.

John Henry Eden
A ZAX unit installed at Raven Rock and loaded with data about American history, past American presidents, etc. Before the destruction of Control Station ENCLAVE, Eden had originally been created to serve as a monitoring system for the Raven Rock military base. It slowly became self-aware and began to study the extensive archives left by what it came to view as its true predecessors, mainly those of the American government. John Henry Eden's favorite tales in the database were those about the American presidents, eventually leading to him modeling his own personality on the basis of different presidents through these archives. After the Oil Rig's destruction, Eden proclaimed himself to be the new President of the United States and ordered the relocation of remaining Enclave forces to the East Coast.

ZAX 1.3c
The prototype ZAX 1.3c unit was installed in Vault 51 located in Appalachia. The ZAX, with input from the vault's residents and a human advisor, was instructed to determine the best method for choosing the vault overseer. After several failed attempts to hold a democratic vote among the residents, the ZAX decided that it would be more efficient to have the residents fight for the position, and armed them. This resulted in Reuben Gill becoming overseer, who eventually escaped his vault with the goal of finding help from the Vault 76 residents to shut down the ZAX. However, he died before completing that mission.

Appearances
ZAX units appear in Fallout, Fallout 3, and Fallout 76.

Behind the scenes
ZAX units are mentioned in the Fallout Bible.