There is a huge variety of myth about Hellhounds, which is conflated with a huge variety of myths about another spiritual creature. So if you’re specifically looking for hellhounds, here is what I know:
The most famous hellhound is probably Cerberus; from Greek mythology; pet of Hades and guardian of the Gates of the Underworld.
Here are the two other specific “hellhound” myths I know of:
Garmr is a black dog from Norse mythology that guards the gates of the underworld and plays a role in Ragnarok; he (sometimes quoted as a she, actually) is Hel’s pet and guardian of Helheim where she resides. Garmr’s howling is used as a sign that Ragnarok (Norse Apocalypse) has begun.
The Cwn Annwn (are there Welsh readers out there? How do I spell/type this properly, I tried to find out and I’m so lost, I made my best attempt) are faerie hounds; and probably the most benign; they often appear with migration of birds and their howls in the mountains of Cadair Idris fortold death; they have a ‘reverse’ of sound in that the softer they growl, the closer they are. They are also seen as the escorts of souls to the afterlife, and also often associated with the Wild Hunt. Sometimes they have mirrors for eyes.
However, if you’re willing to take Hellhounds by another name in regional folklore:
Black Dogs make an appearance in pretty much every part of Great Britain (and certain other areas of the world, but Great Britain is where they are a household name). Typical for folklore, there’s a lot of regional variation. There’s things that are agreed on - they are omens of death; their eyes are red or yellow and abnormally large, they are hellish/related to the afterlife/other worlds. They are often associated with lonely roads and crossroads.
Past that, however, there’s mostly regional tales about the dogs with different powers attributed to them. Black dog myth ranges from ‘guardian’ to ‘howls and people drop dead’ to ‘kills people actively’. I’m going to talk about regional variations here since there’s no real solidity to black dog myth. So without further ado, here’s a list of real folklore black dogs:
- The Cadejo of South America (Stephen King’s ‘Cujo’ inspiration, although Cujo if I recall properly wasn’t black), a black beast that follows the unwary that take lonely paths at night. Benign but threatening.
- Catalan’s Dip, a vampiric black dog with a foul odor, associated with demons and lame in one leg.
- Black Shuck, of Norfolk, Essex, and Suffolk coastline area; occasionally said to have green eyes, sometimes a protector of women on a trip home, but often an omen of death in the family. Associated with crossroads, graveyards, and forests. Killed two people in a church at Bengay, leaving scorch marks on the door and collapsing the tower.
- Gytrash of Lincolnshire, leading people astray in the mist if they were late.
- Church Grim/Kyrkogym from Sweden; black dogs were often buried alive (D:) to create guardian spirits for new churches.
- Yeth hounds, Devon spirits of headless black dogs that are supposedly unbaptised children’s spirits, wailing in the woods.
- Gwyllgi, a black welsh mastiff with flaming eyes and foul breath.
- Barghest, a Yorkshire dog with huge teeth and claws, alternatively taking the form of a headless man, a rabbit, and a regular dog.
- Gabriel hounds are the Lancashire version of the Cwn Annwn often cited as having wings.
- Not black but dark green, the Cu Sith was a mossy fairy dog with a curled tail and flaming eyes. In Irish myth, however, it is black, and had a terrifying bark that was a warning to lock up your family.
- Somerset has a Gurt Dog that protects children traveling alone.
- Norse mythology had black dogs too! If one appeared on your hearth it was in your best interest to care for it for a year.
- If you think about it, Anubis can be seen this way too. Jackals are canines. Also, he has a wolf cousin, IIRC, Wepwawet.
IN FICTION (strap on your seatbelts kids, there’s a lot):
- The Grim/Sirius Black of Harry Potter fame, clearly taken from the Church Grim, but showing traditional ‘dog of death’ folklore signs. Also, Fluffy.
- Hellhounds from Supernatural, dragging people to hell; also of note is that Crowley says “nobody knows more about the hounds then I” and he is, after all, king of the crossroads.
- The “Hound of the Baskervilles” Sherlock Holmes story is inspired by legends of ghostly hounds.
- Houndoom the Pokemon is a reference to Hellhounds.
- The Wheel of Time has darkhounds, massive black shadowspawn with saliva that kills when a drop touches the skin, and never give up.
- Alucard, of Hellsing, has a black dog form that is definitely supposed to be a Hellhound.
- The first Hellboy movie has an antagonist hound named Sammael.
- Piers Anthony’s “On A Pale Horse” has Death controlling Hellhounds.
- In Faust, Mephistopheles first shows up as a black poodle.
- Good Omens has a hellhound hilariously named ‘Dog’.
I have missed A LOT - in fiction and in real folklore - but you can see why. THERE ARE LOTS. And some overlap.