By creating the illusion that the outside world was completely uninhabitable with fake radio transmissions often spilling in, his task was to reinforce that the vault dwellers' only hope of survival was in the vault. In consequence, he prevented anyone from leaving the vault.
The Overseer died of natural causes 50 years after the bombs fell in 2077 at the age of 84. Before his death, he prepared a subordinate to continue the vault experiment, Vault 101's second Overseer.
Vault 101's original Overseer is mentioned only in the Fallout 3 Official Game Guide.