Beithir the Lightning Serpent
An electric column about folklore and tabletop RPGs
If you ever visit Scotland, it’s not just the lochs and riverways that you need to tread carefully by. For amongst the corries and dark caves of the Highlands lurks the beithir, a most venomous and destructive creature.
If you’re familiar with D&D’s behir, this is the legend behind the monster.
The beithir is, put simply, “the largest and most deadly kind of serpent”1. It has dragon-like qualities, but instead of wings or fiery breath it’s equipped with a venomous stinger. If stung, you better be able to beat the beithir in a race to the nearest body of water—if you jump in first, you win; if it gets there first, you die.
The word beithir is Scottish Gaelic and can mean "serpent", "lightning", or "thunderbolt"—the latter two being the likely origin of the D&D behir’s lightning breath. Alternatively, the creature is also referred to as the beithir-nimh (venomous serpent) and the nathair (serpent + adder).
Habitat & The Fuath
The beithir can typically be found haunting caves and corries (a round hollow in a hill or mountain), which makes it a natural fit to lair in a dungeon. Beithir are also said to be sighted following lightning strikes2. Lightning might attract beithir, or beithir might attract lightning. The lightning could even create them! Alternatively, perhaps beithir are drawn to lightning strikes in order to feed on or absorb the ozone they create. I’d even suggest that this lets them produce lightning themselves, but at that point, whoops, we’ve just created the behir again.
Some folklorists classify beithir among the fuath3—malevolent Scottish spirits, often those associated with water. Given this, it wouldn’t be out of character to be seen in the company of other such creatures. Perhaps a particularly awful beithir might arrange that if a poisoned victim manages to escape, it at least knows a kelpie lurks in the nearest body of water.
Wicked Stepmothers At It Again
A traditional story of the beithir that positions it in a different light to just being a simple monster was recorded by John Francis Campbell in 18904. In this folktale, a wicked stepmother gives her new son (an Irish prince) a magic shirt that’s actually a beithir in disguise. Once the snake wraps itself around his neck, the prince comes under his stepmother’s enchantment until a wise woman and her lovestruck daughter conspire to free him. The beithir does bite off one of the daughter’s breasts in the process, but sometimes you have to make sacrifices for love. The prince makes her a golden breast at least, and they both live happily ever after.
Using Beithir in Your Game
With themes of poison, electricity, and being a f**k-off giant serpent, there’s plenty of ways to incorporate a beithir into your game.
On its own the beithir is a dangerous and destructive creature—the kind desperate villages seek to employ adventurers to deal with. Alternatively, it makes an effective guardian due to its venomous power and predisposition to lurking underground. Give it cracks in the ceiling to squeeze through and a beithir could easily be justified as nesting in an unoccupied (or, ah, previously occupied) room in a dungeon.
Storm of the Century
Over a hundred years ago, a once in a generation storm caused a swarm of beithirs to emerge from beneath the earth to menace a small town. Now, the dark clouds on the horizon threaten a repeat of that dreadful night. Will the party be able to somehow intervene first, or will they need to help this town as it falls under siege from both nature and monster? This sort of hook can be used in any setting, and might make a particularly fun one-shot in a horror-focused game as a party of normal townsfolk struggle to hold back an onslaught of bestial serpents.
A strong hook for using the beithir in a modern game is connecting their link with lightning to electricity. In a Tales from the Loop game, the beithir could be a creature that poses great risk if it’s attracted to (and attacks) robots in a small town. In a cyberpunk or high-tech urban fantasy game, perhaps beithir are creatures that have evolved to feed of electricity. If we shrink them down, they could even be the futuristic version of termites, doing catastrophic damage if they get into a power station and disrupt the electrical grid.
Some rare beithir have the ability to enchant those they constrict, shrinking down to perfectly coil around their victim’s neck. Perhaps someone of importance, or at least important to the party, begins to act contrary to their usual nature due to a beithir wrapped around their neck. The beithir might have its own agenda, or be acting as a dangerous tool for someone powerful enough to command it. Magic-users employing a beithir often glamour them once in place to make their presence hard to spot and harder to prove. Knowing the beithir is there is only half the battle, of course, since it can always threaten to kill its victim if backed into a corner. A magical or particularly clever solution is likely in order.
Beithir Statistics (Old-School)
Armor Class: 6 
Hit Dice: 5* (22 hp)
Attacks: 1 x bite (1d6 + constrict) or 1 x stinger (1d8 + venom)
THAC0: 15 [+4]
Move: 120’ (40’)
Save As: Fighter 6
▶ Constrict: When a slam attack is successful, the beithir wraps around the victim and begins to squeeze, inflicting 2d4 automatic damage immediately and on each subsequent round. While constricting a victim, it defends against other attackers with its stinger.
▶ Venom: Save versus poison or die in 1d6 turns. The only cure is submerging oneself in a body of water (such as a river or lake).
▶ Spoil: When the beithir touches a liquid, it removes all its curative or healing properties. If it touches a body of water, that water cannot cure its poison for 24 hours.
Some beithir have the special power to enchant those they constrict, forcing a recurring save versus spells instead of inflicting automatic damage. On a failed save, they shrink so they can remain tight around their victim’s neck and gain complete control of the victim’s actions.
And that’s it for the beithir! If you take nothing else away, make sure you practice sprinting and know exactly where nearest body of water is. Backyard pools will probably do in a pinch.
Thanks for reading; come back next week for another fantastical piece of folklore to use in your role-playing games!
Penny for your thoughts: What’s the nastiest snake or serpent you’ve seen in a role-playing game? Did you run it or have to face off against it?
~ A.C. Luke
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Campbell, John Gregorson. 1900. Superstitions of the Highlands and Islands of Scotland. James MacLehose and Sons: Glasgow.
Bane, Theresa. 2013. Encyclopedia of Fairies in World Folklore and Mythology. McFarland: Jefferson.
Mackillop, James. 1998. Dictionary of Celtic Mythology. Oxford University Press: Oxford.
Campbell, John Francis. 1860. Popular Tales of the West Highlands. Edmonston and Douglas: Edinburgh.