Grey

He looks like a farmer. Sturdy pants, worn boots, rough-spun shirt, a wide-brimmed hat that might put him anywhere between thirty and fifty. Soft-spoken, as Quiet Folk tend to be. The kind of man you would sit beside at a bar and forget by morning. That is the design, and it is flawless.
  Grey, known as Uncle Grey to the children of Yesterday, is the most well-rounded killer in the settlement. He teaches guns, knives, longer blades. He teaches how to turn any object within arm's reach into something that ends a life. He teaches punches and kicks that disable, that cripple, that kill. The youngest children learn from him first, and what he gives them is not just technique but instinct: the understanding that everything is a weapon, including stillness, including silence, including the appearance of being no one at all.
  When Grey leaves Yesterday on what he calls sabbatical, the rough farmer disappears. In his place might stand a well-dressed city man from Vegasia. A gang enforcer from Old York. A sailor from Beacon Hill. The transformation is instant and total. On sabbatical, Grey is unrecognizable, which is the entire point. He works quickly, finishes the job, and returns to Yesterday before anyone thinks to connect the unremarkable farmer with the death that just occurred three settlements over.
  He is well-respected within Murder Inc, though he refuses to acknowledge it. Mention his reputation and he will shrug over his drink and say, "Then I guess they got poor taste." The humility is genuine. Grey does not care about legend. He cares about the next generation, and about the work, and about doing both well enough that no one ever sees him coming.