Billy was a friend of the wastelander trapped inside the Dunwich Building.
This wastelander was trapped in an office room in the Dunwich Building. Billy was meant to bring his friend frag grenades and ammunition, but was still not seen three days later. His skeleton, along with two grenade boxes, can be found at the entrance of the Dunwich Building. What happened to his friend is unknown.
Billy is mentioned only in Fallout 3.