Character from Shadow and Bone by Leigh Bardugo
Shadow soldiers summoned from the void — the Darkling's personal army of darkness that obeys only his will and cannot be killed by conventional means.
The nichevo'ya are the Darkling's ultimate weapon — created through merzost like the Fold, but refined into something controllable. They are shadow given form and purpose: soldiers that obey only his will, cannot be killed by conventional weapons, and leave wounds that Healers cannot close. They are the Darkling's answer to every army, every alliance, every threat: infinite, tireless, and loyal in a way that living soldiers can never be. Their creation further drained his humanity, pushing him further from the man he was toward the monster he became.
Humanoid shapes of living shadow — featureless, dark, terrifyingly fast. They emerge from the Darkling's shadow and return to it. Their attacks leave wounds that cannot be healed by Grisha methods.
Also known as: Nichevo'ya, Shadow Soldiers, The Nothing