A black dog or Grim is one of a number of supernatural beings said to haunt lonely stretches of road, execution places, and churchyards of the British Isles. Although usually not outright harmful towards people, they are still typically seen as sinister, if not outright malevolent. They are often considered to be omens of an upcoming death.

Their common motif is that of a black-colored dog, but they can also appear in other forms, such as a black horse, a cow, a white dog (), even a headless dog with blazing eyes. Different dogs can have different origins, from hounds of the Devil to executed prisoners to dogs sacrificed in a churchyard to serve as guardians against the Devil and other malicious creatures.

A common behavior among black dogs is walking behind a lonely nighttime traveler, often with noisy footfalls making a trash, trash, trash sound. If one turns and confronts the dog, they can die.

The church grim is a rare example of a benevolent black dog.

For more information:

• Black dog (Wikipedia))