- Venomous snakes have long held our imagination's enthrall.

And it makes sense.

To this day, humans fall prey to their natural defenses.

Secretive, slithering, seductive and scary, the serpent has claimed a prominent place in our literature, our religion and even natural history.

And there are few serpents more frightening or pervasive than the king of snakes, the mighty basilisk.

I'm sure for some of you when you see this picture, you'll say, "oh wait, that's a cockatrice."

Well, you're not wrong.

That's right, the elusive and terrifying snake monster and the fiery rooster monster not only share origins but are arguably the same monster, just with two different names.

This, this and this are all the same creature.

Technically, even this little one.

But we'll get to that cutey later.

Join me on an exploration of the basilisk-cockatrice connection, and how it went from frightening snake to a metaphor for pure evil.

(lively music) I'm Dr. Emily Zarka and this is Monstrum.

The earliest references to this serpentine monster date back thousands of years to the first century.

In his epic poem "Pharsalia," the Roman poet Marcus Annaeus Lucanus, known in English as Lucan, introduced us to a serpent capable of producing immense terror, writing, "The basilisk which pours forth, hisses terrifying all beasts, which harms before its poison and orders the entire crowd far out of its way and on the empty sand is king."

With a stroke of his pen, Lucan brought to life a terrifying snake whose royal status was firmly established from the beginning.

So lethal, the basilisk venom can kill even after the beast has been destroyed as a solider in "Pharsalia" learns when he stabs the snake and the venom runs up the spear into his hand.

In a moment of foresight, the man slices off his own hand with a sword to save his life.

Pliny's Encyclopedic Historiae Naturalis, or Natural History, contains a similar story, only this time, both the writer and his horse die after the basilisk is speared.

In this text, the blackish-yellow, no more than foot-long snake slithers along with its upper body erect, hypnotizing its prey with eyes sunken into its sharp head.

According to Pliny, the basilisk can kill with its gaze alone, as well as with its noxious breath.

Interestingly, we also learn of the monster's weakness.

The stench of a weasel will kill the basilisk, although the weasel too will perish.

Pliny asserts that the basilisk earns its Greek name, Vasiliskos, and Latin equivalent, Basiliscus, both meaning kinglet for a crown-like white spot on its sharp head resembling a diadem.

In fact, those two early texts, "Pharsalia" and "Historiae Naturalis," laid the foundation for the attributes that have been associated with the basilisk ever since.

That is a venomous snake whose breath, gaze or even hiss could destroy all life, animal, human or vegetable.

Moreover, the origin stories of the basilisk include mention of an ability to summon other snakes with its kiss, even as it frightens off or kills all other creatures.

It's unsurprising then that this powerful decorated snake with it's crown-like spot will be subsequently called the king of the serpent in the Greek poet Nicander's "Theriaca."

Authors and artists in the Medieval period seemed to have taken liberty with the kinglet, depicting the creature with a crown or even a rooster's comb.

Beginning in the 13th century, we find text describing a reptilian monster and even the king of serpents with all of the traits of the basilisk plus a new one, a rooster's comb rather than a crown adorns its head.

And it bears a new name, the cockatrice.

Over time, we see the names basilisk and the cockatrice used interchangeably as the creature becomes more and more like a snake-bird hybrid.

The cockatrice appears in literature and art, in marginalia and coat of arms, bearing a combination of chicken and reptilian features with dragon wings or an extra head occasionally thrown in there for good measure.

It is said to petrify with its gaze or touch of its beak.

With all this fantastic and suggestive imagery around its appearance, it's no surprise that religions would embrace its wealth of allegorical power.

In the Christian tradition, the serpent was already associated with sin and the Devil, due largely to its seductive role in the fall of the Garden of Eden.

So the basilisk, AKA the cockatrice didn't really stand a chance.

Take, for example, an origin story of the basilisk that emerged in the 1100s, which proposed that it is born from an egg hatched by a toad.

The first person to suggest this was St. Hildegard in her book "Phisica."

She even goes as far as to say it is the diabolic art of the ancient serpent that comes from the Antichrist that spawns this unnatural hatching.

Over time, these dubious origins become part of the basilisk and the cockatrice myths, evolving even further to include details like the egg is laid by a rooster and that it would be incubated in a dung heap.

The basilisk became not just dangerous and poisonous but a literal embodiment of evil that must be vanquished.

In fact, a lot of art from the Medieval period shows Christ, a saint or some other holy figure defeating the basilisk or cockatrice but it can still be killed by a weasel, which explains these absolutely delightful illustrations.

And of course, given the shift towards religious allegory and the history of the serpent beast, we see the power of prayer taking hold as another defense against its evil effects.

A bit confusingly, around this time, we learn that carrying a rooster around can also protect you because the rooster's crow can frighten the basilisk to death.

Or if you're quick on your feet, spotting the basilisk before it spots you or showing its own reflection are among your defensive options.

Oh yes, the idea that humans could survive the deadly gaze of the basilisk by looking at it in a mirror had begun to take hold.

So apparently, Harry Potter got that part correct.

Even though Voldemort's basilisk is much, much, much larger than any other depiction of a basilisk in literature or art.

That's artistic license for you.

Interestingly, the deadly gaze of the monster, along with its more negative associations with sin and evil in Christianity eventually led to its allegorical use to indicate both vile scoundrels and dangerously beautiful and seductive women in the 17th century and beyond, which likely goes back to the portrayal of Eve in the Garden of Eden.

Although, there are many other plausible contributing factors, including the myths of Medusa and Lamia, along with, you know, patriarchy.

John Dryden, famous English poet and playwright of the 17th century was one such author.

"The Queen and the Spanish Friar" or "The Double Discovery" is called the "Basilisk Of Torrismond" since she kills with her eyes.

But let's go back to those early origins of the basilisk.

There are scholars who argue that the basilisk of ancient lore was actually a real snake that with time and the human imagination was imbued with more and more traits until it became something utterly fantastical, and completely divorced from its mundane roots.

If it is true as some assert that the early basilisk at one point was believed to be native to Libya, this makes sense.

After all, Libya is home to the Egyptian cobra, one of the most terrifying snakes on the planet.

Cobras are also illustrated in Egyptian hieroglyphics with the middle of the body raised up in a manner that resembles bird feet, which might have later contributed to the cockatrice interpretation of the monster, and which calls to mind Pliny's description of the basilisk's erect upper body.

While the Egyptian cobra is a perfectly serviceable real-life origin snake for our evil serpent, it is not the only candidate for the honor.

Another theory, I offer you the humble grass snake.

The grass snake has a yellow, orange or white collar and its defensive mechanisms include aggressively hissing, secreting a foul smelling substance from the anal glands, and even playing dead.

Grass snakes also happen to love to hatch their eggs in rotting wood, plant debris, compost and dung heaps.

What's most interesting about the grass snake as real basilisk theory is that grass snakes, whole totally common, are rarely mentioned in ancient bestiaries and early animal encyclopedias.

Meanwhile, the fictional basilisk is identified as a species in almost every one of these resources.

This might indicate that the grass snake was at one point misidentified as a basilisk before the latter's evolution to the cockatrice blurred the lines between reality and fiction even more.

To make this even more interesting, the cock's egg origins of the basilisk/cockatrice could be explained by the perfectly normal phenomenons of hens occasionally laying yolk-less eggs or hens acting like roosters because of a hormone imbalance or an unusually dominant personality.

Then there's the occasional appearance of parasitic worms in eggs, which will sometimes look like tiny snakes.

Whether or not the basilisk, AKA the cockatrice was truly based on a real animal is unclear.

What we do know is that we humans have been fascinated with the idea of the basilisk for centuries.

So much so that they have permeated into our literature and art.

To this day, the basilisk and cockatrice live on in books, D&D, video games and film.

And coming full circle from its vaguely reptilian associations, there are real modern lizards named after this fantastic beast.

Four species of lizards, in fact.

They're in the Iguanadae family and the genus Basiliscus, better known as casthead lizards.

Their common names include the brown or striped basilisk, the western basilisk, the common basilisk and the plumed lizard, whom you may also recognize as the Jesus lizards for their ability to run across water.

This seems particularly ironic given the basilisk's one-time association with the Devil.

While these lizards have no powers that allow them to cause death with a glance, they do have a long tail and an elongated head that looks like a rooster's comb.

Just another way monster history infiltrates our real world.

The basilisk and the cockatrice have thrived in our imaginations for a very long time.

From king of the serpents to sin incarnate, to metaphor for the exaggerated dangers of a woman's allure, these serpentine avian monsters both fascinate and repel, their lethal gaze lingering from the pages of antiquity into our modern world.