Buck Nixon was a foreman working on The Rockhound for Hornwright Industrial Mining. A veteran, so to speak, Nixon worked on the excavator while it was still hooked up to the local power grid, supported by Diesel engines. When Hornwright replaced the unreliable, expensive power supply with the cleaner, more efficient four nuclear reactors, he was elated to have a machine that didn't stall every other moment. While living by nuclear reactors, shielded as they may be, was a bit of a problem for him, Buck enjoyed a stable job and fat bonuses that convinced him and his crew to stay.
Buck Nixon appears only in Fallout 76.