Angel of Death

Also called carperi, angels of death are sent to collect souls incredibly valuable to or desired by divine powers who don't want to risk the souls getting lost or intercepted.
Angels of death are often dispatched by their masters when those divine forces feel as though a mortal creature unfairly escaped a deserved death because of good fortune, unwarranted divine interference, or resurrection magic. These angels are often seen in the aftermath of accidents or other unfortunate events where someone survives against incredible odds.
Angels of death are patient, and they might watch a doomed creature for days or even weeks, waiting for a fatal blow to come. Doomed creatures may see out of the corners of their eyes the magically disguised angel lurking and hiding, but the angels disappear when the doomed tries to find them. If an angel fails to harvest the soul of its intended target, it pursues that target until the target is dead or the angel of death is defeated.
An angel of death is a six-foot-tall bipedal creature with a skull for a head and a desiccated, zombielike body. Its gangly limbs emerge from a tattered tunic and torn, dirty breeches. It holds an oversized scythe in two clawlike hands. The skeletal head wears a mask of an eerily smiling face of the same species it is pursuing. An angel of death often disguises itself as a humanoid in modest peasant clothing carrying a modest farming implement.

Many commonfolk pray to the angels, lifting their tear-streaked faces to the sky in search of a powerful being who can fix their problems, remedy their grievances, or show them mercy. What the gods who answer those prayers fail to reveal is that the angels sent on their behalf are often more terrifying than the demons and devils everyone fears. These horrors are creatures of celestial provenance that are either terrifying in their natural form or warped versions of their benign selves through interactions with ever-demanding mortals.