Hollow Skull Vulture

The vultures can smell death, or so the locals believe. Skeletal beasts with ragged feathery wings, glowing eyes to fill empty eye sockets. The Hollow Skull Vulture is the herald of death in the north. Death may have created humans, but he doesn't offer a loving embrace. Rotting flesh sloughs off the creature's body, and its gizzard distends from its emaciated neck. The head is just a skull, and when the bird is at rest, the eye sockets are dull and empty. Two tiny clawed arms protrude from its chest like something is trapped inside and trying to escape. According to popular belief, those arms hold the soul in place while the vulture eats away at the body.
Sharp talons cut through bone, and anyone unlucky enough to be cut by one of these vultures finds that the wound only festers and decays. They usually hang around graveyards feasting on the unburied dead. They're also common in the mountains and seem to be the source of Frost Ghouls. They enjoy the decaying flesh of sapient beings most of all. The birds don't caw but rather moan like they're in agony. It's an eerie sound to hear late at night. In the land of the dead, the birds are everywhere, but they look quite a bit different. Their bodies are fully filled out with healthy feathers and piercing yellow eyes. The sight of them is still chilling as they sit over doorways and guard arches, but they aren't the undead abominations that most people are familiar with.
Killing them is a challenge. They're immune to necromancy and other magical effects. However, a good old fashioned arrow to the chest will take one down. Stealth is the best way to go because once they're airborne, they're fast and difficult to catch. A sword can cut off the head to kill them, but that also risks being within striking range of their talons. The most common course of action is to avoid them. So long as one isn't at risk of dying soon, they leave people alone.