The legend of the hell hound is wide spread and mostly the same in many cultures. It's said to be a large black dog and often has the qualities of super-strength and speed and often smells very unpleasant. It also commonly has glowing red eyes and can appear and disappear at will. The hell hound is tasked with taking souls into the afterlife once a person has died. In a small number of legends about these creatures, its thought that they can be controlled by demons or the devil and have to do their bidding.
Although this legend is mostly easily followed through European history, dating back to the vikings, the lore is also found in the America's, it's just better documented in Europe.
They have many different names and are referred to by many colloquial terms but they are always thought to have the ability to be very dangerous and affiliated with evil.
Hell hounds are said to be repelled by a number of cleansing agents, including holy water, gofer dust and devils shoestring.