Bill Garrahan was the elder brother of Bryce Garrahan and elder son of Vivian Garrahan, CEO of the company. A tinker with an uncomplicated view of the world, Bill occupied himself primarily with expanding his ever-growing collection of firearms and plotting what he would do with the company he was slated to inherit. His bad attitude went hand in hand with the inability to read people and a shaky moral backbone. Bill hated Brighton Gould, believing him to be a gold digger (he wasn't), and despised miners striking for better wages and working conditions as communists. Unfortunately, as an idle rich collector, he had all the time and money in the world to come up with dumb ideas. When the miner riots hit, Bill took it upon himself to defend the Garrahan Estate with a shotgun of his own. Enamored with the feeling of might it gave him, he went on to commission the Strike Breaker: A 2000 rpm mini gun to use against the rioters. And then, on October 12, 2077, he promptly went and decided to give the National Guard a hand, shooting up the Rockhound with it and hurting the negotiation process his brother, Bryce Garrahan, has just finished.
Bill Garrahan is only mentiond in Fallout 76.