John Hancock is a ghoul who resides in the settlement of Goodneighbor, serving as its unofficial mayor. Born John McDonough, Hancock is the estranged brother of Diamond City's mayor, Mayor McDonough; the then non-ghoul John cut ties with his brother after the mayor banished all ghouls from Diamond City, resulting in the deaths of numerous innocent ghouls as the city turned on them. John tried to help as many ghouls as he could relocate to the town of Goodneighbor, attempting to save as many lives as possible, but many couldn't adjust to Goodneighbor. Their deaths would continue to torment him into the present day. John relocated to Goodneighbor, viewing it as a place for those who didn't fit in anywhere else. He is exceptionally punitive toward his enemies or those that break Goodneighbor law, but can be a good friend and valuable ally to those who treat him with respect, punish the guilty and protect the innocent.

He became a ghoul sometime after 2282, following the use of an experimental radioactive drug. In spite of his ghoulification, John Hancock considers the high "so worth it," as well as noting the near immortality he obtained as a benefit. Before John Hancock became mayor, the town was run by a ruthless mob boss named Vic. After witnessing the death of a fellow drifter by Vic's henchmen, John got high and passed out. When he came to, he found the clothes of the real John Hancock and, inspired by their presence, he took it upon himself to raise a militia and overthrew Vic from power. From then on, he became John Hancock, the mayor of Goodneighbor.

Currently, Hancock serves as the self-appointed mayor of Goodneighbor. The majority of citizens look to him for guidance, and he acts as a source of reassurance concerning the looming synth threat.