Hellhound (X-Files)

The Hellhound is the third and arguably most terrible of the villainous entities in the infamous X-Files episode "Familiar" - though it plays second to the episode's true antagonist, Mister Chuckle Teeth : the creature is based on the hellhound of folklore and is the means by which Mister Chuckle Teeth kills his child victims.

History
the Hellhound part of a demonic force that manifested into the world after a witch cast a spell on her cheating husband designed to cause him harm, yet her spell backfired horrifically and the demon(s) she summoned instead began to target those she loved : such as the town's children.

In order to lure children to their deaths the force would manifest as popular child mascots such as Mister Chuckle Teeth and Biggle Tiggles, taking the children deep into the forest - once in the forest and away from prying eyes the demonic force unleashed the Hellhound, which would promptly pounce upon the child and maul them to death before brutally mutilating their body.

Like all aspects of the demonic force the Hellhound is presumed to have been banished when the witch ultimately killed herself in an effort to reverse the curse but in typical X-Files fashion the ending shows playground equipment start by themselves, suggesting the demons are still active and waiting to strike again.

Appearance
a large black wolf with a sinister way of lurking in the forest, the hellhound embodies both the ancient fear of wolves and the legend of "black dogs", which were seen as omens of death and misfortune in medieval Europe.

Abilities
as an aspect of Mister Chuckle Teeth the Hellhound is immortal, invincible to most earthly assaults and for all intents and purposes an omnipotent being - however, it is also chained to the world via magic and the death of its summoner seems to weaken it, if not banish it completely - while Mister Chuckle Teeth and Biggle Tiggles are shown as the aspects used to lure children it is the Hellhound that ultimately manifests the violent and raw power of the demon, able to mutilate children in moments and leaving their horrific remains for adults to find and thus spread panic and fear.