Sinjin

Sinjin is a character in Fallout 4 who serves as the main antagonist of the side quest The Silver Shroud. He is an intelligent ghoul and a Raider leader who, through a network of subordinates and contacts, heads a criminal operation throughout the ruins of Boston and it's outskirts.

Background
Not much is known about Sinjin's background other than his criminal network, but he is described by John Hancock as much more ruthless and brutal than an ordinary raider leader, capable of amassing a unstoppable militia if given the time. Because of this, Hancock is worried about him and plans on dispatching him before it's too late.

Sinjin has a criminal network of chem pushing, contract-killing and loan-sharking through various subordinates, each one being more important than the other and more protected.
 * Wayne Delancy: Sinjin's agent in Goodneighbor who deals with people who don't pay on time.
 * AJ: Sinjin's chem dealer in Goodneighbor.
 * Kendra: Sinjin's hitman.
 * Militia: Led by Smiling Kate and Northy, Sinjin has a personal militia to dispose of any annoyances.
 * Avery: Sinjin's right-hand woman.

Fallout 4
The Sole Survivor (player character) begins to work with Kent Connolly to clean the streets of Goodneighbor and disguises himself as "The Silver Shroud", a comic book vigilante who wears a black trenchcoat and fedora and wields a silver Tommy gun. Initially, both of them think that their targets are just unaffiliated criminals, but Mayor John Hancock informs them that Sinjin is the boss of their targets.

After the elimination of most of his subordinates, Sinjin plots his revenge and amasses an armed militia, planning to raid Goodneighbor and burn it to the ground. He hires Smiling Kate and Northy, tasking them with the elimination of the Silver Shroud. However, both of them are eliminated as well by the Shroud before they can carry on their task.

Furious, Sinjin snatches Kent and sets his stronghold at Milton General Hospital, to the south of Boston. The Shroud then breaks into the hospital, kills most of Sinjin's men and finally confronts him. From here on, there are several different outcomes, but all of them lead to Sinjin's death.