Thessalhydra

Night in a swamp, and something is breathing in eight places at once. The necks come up out of the water slowly, each one about as long as a man is tall, each ending in a flat reptilian head with its jaw slightly open. They do not turn together. They drift and correct independently, the way eight separate animals would, and the effect is of being watched by a committee. Below them, where a head ought to be, there is a mouth: a circle of teeth set into the top of the body, rimmed with saliva that smokes faintly where it drips onto wet leaves.

That mouth is the point of the whole creature. The eight heads are teeth on stalks and their bites carry a poison strong enough to drop a man where he stands, but they are not what kills. Some distance back, the tail is doing the real work. It runs perhaps eighteen feet, thick as a fallen trunk, and it ends in a pair of pincers that open wide enough to take a body around the ribs. The thessalhydra grips, lifts, and folds its catch forward into the waiting circle of teeth, and the acid does the rest. The colouring across the family runs dark green, blotched with yellow, with the occasional startling tuft of reddish hair.

None of this is old. The thessalhydra has no village that feared it and no manuscript that first names it. It was invented by Gary Gygax and published in August 1983, on page 119 of the Advanced Dungeons & Dragons Monster Manual II, with an illustration by David C. Sutherland III that fixed the squat, wrong-shaped body every later artist has copied. The name is a portmanteau and nothing more mysterious than that.

Inside the fiction, though, it was given a genealogy, and the genealogy is stranger than the monster. A 1989 supplement set out a small family called the thessalmonsters and traced all of them back to one extinct ancestor whose distinguishing gift was that it could breed with almost anything. That ancestor was a thirty-foot reptile with the same circular mouth and the same pincered tail but no crown of heads at all. Cross it with a hydra and the result is a thessalhydra. Cross the thessalhydra with a chimera and the result is a thessalmera; with a gorgon, a thessalgorgon; with a cockatrice, a thessaltrice. The book is candid about the one thing it cannot explain, which is the word itself. By the time anyone in the setting thought to ask, the meaning of “thessal” had been lost, and opinion was split between a place where the creatures were first seen and a person who made them. A Dungeon magazine adventure in 2006 supplied the person: a lich called Thessalar, working in a place named the Wormcrawl Fissure. Whether that is an answer or a retrofit is a matter of taste.

They are kept, occasionally, as guards. A juvenile chained at the mouth of a vault needs no training, because it will attack anything that comes near it regardless, which is either the appeal or the flaw depending on who owns the vault. Down there the air stays warm and close and smells of wet stone and something sour underneath. Adults are voracious enough to eat one another, so nobody keeps two.

The creature would have stayed a footnote in a hardback most people never opened if not for a basement in Hawkins, Indiana. In the last minutes of the first season of Stranger Things, released in July 2016, four boys sit around a card table a month after the worst thing in their lives, running a Christmas campaign. Mike leans over the screen and tells them something angry and hungry for their blood is almost here. Dustin knows what it is before it arrives, and says so twice, and Lucas tells him he is wrong. Then the figure comes down on the table with a thud and Dustin is not wrong any more. The fight that follows lasts about forty seconds of screen time. Will the Wise throws a fireball, rolls a fourteen, and the thing crumbles to the ground with one clawed hand reaching. Lucas cuts off its seven heads, Dustin stows them in his bag of holding, and they carry the heads out and present them to King Tristan, who thanks them for their bravery and service. There is a medal ceremony. Mike is then told, immediately and by everyone, that the campaign was way too short. It had run ten hours.

Mike gave the creature seven heads and a clawed hand. The book gives it eight heads and no hands at all. Nobody at that table was checking, and neither was anybody watching.

The scene did something no monster entry has any right to expect. Attention for a 1983 hardback creature went vertical, fans spent a year insisting the appearance was a coded preview of the next season, and in May 2019 Wizards of the Coast and Netflix put out a Stranger Things starter set dressed to look like the old red box, built around an adventure called Hunt for the Thessalhydra. A monster invented for a book was borrowed by a television show and then written back into the game because the television show had made it famous. Not many creatures get to be their own sequel.

Its advantages are all close range and all patient. Eight heads bite independently, so it fights eight opponents at once without dividing its attention. Its own acid cannot hurt it, and neither can poisons that work by burning, which means it can flood a corridor and walk through the result. Once a day it spits, and the spray covers a wide patch of ground at a considerable distance, ruining armour and skin together. A severed head grows back, which is the detail everyone remembers.

The regrowth is also the limit. A lost head takes twelve days to return, and twelve days is not a threat, it is an inconvenience. This is not the Lernaean hydra, sprouting two for one while the hero watches. Enough heads taken quickly enough, and the creature simply has fewer heads. The acid comes once and then it is gone. The bulk that makes the pincers work also ties it to swamps, jungles and the dark under the ground where the damp is; it does not climb, it does not fly, and it cannot hide. Worst of all for its own species, it will eat another thessalhydra as readily as it eats anything else, so they never arrive in pairs. It is a monster built to be killed by five people with dice, and eventually it always is.

Frequently Asked Questions

What is a thessalhydra?

A thessalhydra is a monster from Dungeons & Dragons: a huge dark green reptile with eight hydra-like heads arranged in a ring around a circular, acid-filled mouth set into its body, and a long tail tipped with pincers. It has no head in the ordinary sense. It bites with all eight heads at once, spits acid once a day, and uses its tail pincers to lift prey into its central maw.

Is the thessalhydra a real mythological creature?

No. The thessalhydra is a modern invention with a known author and date: Gary Gygax created it for the Advanced Dungeons & Dragons Monster Manual II, published by TSR in August 1983. It has no basis in folklore or ancient myth, though its design borrows openly from the Greek hydra.

What happens to the thessalhydra in Stranger Things?

The thessalhydra is the monster in the Christmas Dungeons & Dragons campaign that closes the first season, released in July 2016. Will’s character kills it with a fireball on a roll of fourteen, Lucas cuts off its seven heads, and Dustin puts them in his bag of holding before the party presents them to King Tristan. The scene gave a nearly forgotten 1983 monster a second life, and in 2019 it got its own official adventure, Hunt for the Thessalhydra.

Can a thessalhydra regrow its heads?

Yes, but slowly. A severed head grows back over about twelve days, which makes the thessalhydra very different from the Lernaean hydra of Greek myth, whose heads regrow immediately and in pairs. In a fight the regrowth is useless to it, so cutting off heads faster than they return is the straightforward way to beat one.

What are the other thessalmonsters?

There are four: the thessalhydra, the thessalmera, the thessalgorgon and the thessaltrice. All are hybrids descended from a single extinct ancestor that could crossbreed with almost anything, and the last three are the offspring of a thessalhydra crossed with a chimera, a gorgon and a cockatrice respectively.

Related Entries

Lich, Hydra, Chimera, Gorgon, Cockatrice, Basilisk, Manticore, Ladon, Typhon, Echidna, Yamata no Orochi, Tarasque, Wyvern, Dragon