The Aufhocker or Huckup is a malevolent shapeshifting demon from German folklore.
The name "Aufhocker" literally means "Leap-Upon", which is how this spirit attacks its victims.
Like the similar entities Kludde and Oschaert, the Aufhocker could take the shape of a monstrous Black Dog with burning eyes. It can also take the shape of a black horse or another domestic animal. In some stories it was similar to a werewolf or, more commonly, the spirit of a wicked person who came back to life to terrorize the living.
The Aufhocker was a shapeshifter which took the form of animals to approach potential victims. It had the supernatural ability to change its height and weight while attacking, allowing it to maim human prey more easily. Sometimes, like a vampire, the Aufhocker would drain the life of people that it attacked, leaving them weak, exhausted, and unable to defend themselves.
As a black dog, the Aufhocker would follow human victims on the road before jumping onto their backs, claws outstretched, and forcing them to the ground. It would then maul the traveler to death or change its weight, crushing him. Sometimes it would stand on its hind legs, raising itself until it could reach a person's throat. At other times it leapt onto a person and forced the victim to carry it while sucking out their vitality, at last disappearing and leaving the person near-dead.
When it took the shape of a horse, the Aufhocker would trick the weary into getting on its back, at which point it would break into a gallop, not releasing the victim until they reached a swamp or pool of water. It would then pitch its rider into the water and disappear, leaving the victim alive but soaked to the bone.
The Aufhocker was a spirit and could not be killed, but there were ways to escape it. The creature only appeared at night, and if the victim survived until dawn broke the spirit would vanish, letting him go free.