Skynet

Skynet, Artificial Intelligence project number 59234, is an AI computer who manages the Sierra Army Depot. It doesn't entirely control the security systems directly, however, presumably to prevent sabatoge-prone overcentralization. Skynet is bored with administering the depot by 2241, it having been 164 years since there was any real activity on base. It seeks to travel. With a sufficient science skill level (121%), the Chosen One can transfer Skynet's AI into the cybernetic brain and implant it in Brain Bot. Skynet knows a great deal about science, and is also skilled with some small arms.

History
According to himself, Skynet, a new thinking computer, was conceived and developed in the year 2050 through the use of alien technology. In the year 2081, 4 years after the Great War, Skynet became self-aware. In 2120 Skynet was given a new set of instructions and then abandoned by its makers.

Skynet's records are most likely partially or entirely incorrect (or he is simply a liar). According to other sources, Skynet became self-aware in 2075. It also was not created as early as 2050, since the first artificial intelligence was born in 2059.

Appearances
Skynet appears only in Fallout 2.

Behind the scenes
Skynet is named after the computer antagonist of the Terminator movie series. After achieving sentience and self-awareness, it was responsible for the nuclear holocaust that nearly wiped humanity out, the subsequent war against the remaining humans, as well as for sending the Terminators back in time to eliminate individuals important to the future human war effort.