"Night gathers, and now my watch begins. It shall not end until my death. I shall take no wife, hold no lands, father no children. I shall wear no crowns and win no glory. I shall live and die at my post. I am the sword in the darkness. I am the watcher on the walls. I am the shield that guards the realms of men. I pledge my life and honor to the Night's Watch, for this night and all the nights to come."
―The Night's Watch oath.

The Night's Watch is an extralegal military order dedicated to manning the fortifications of, and defending, the Wall, the large superstructure of ice seperating the Seven Kingdoms from what lies to the far north. Founded sometime during the Age of Heroes, the Night's Watch was established following the Long Night to protect the Wall that Brandon the Builder had built, and to ensure the Others never returned. Members of the Night's Watch wear only black, and when joining the Order, the action is described as "taking the black". Members are pejoratively referred to (especially by wildlings) as "Crows", due to their sigil. Originally a powerful order of elite warriors, centuries of inactivity beyond the Wall, as well as Aegon's conquest and the numerous preceding and succeeding it, has caused the Night's Watch slow decline, allowing it to become depopulated, poorly regarded and largely neglected.

By the time of Robert Baratheon, the organization is a shadow of its former strength: barely a thousand members, most of which were not warriors: to keep their numbers consistent, dedicated recruiters had to be sent out to gather criminals who chose to join the Watch rather than suffer retribution: this made the Watch more like a prison than a respectable order.