Of all the creatures of legend, few were more feared than the basilisk. It was said to be a small serpent, no longer than a man’s hand, but so deadly that its glance could kill a man, its breath could split rocks and wither grass, and its venom could travel up a spear and kill both the rider and the horse. It was the “king of serpents” — its name comes from the Greek basiliskos, “little king” — and every other snake fled from its hissing.
Over the centuries the basilisk changed shape. By the Middle Ages it had become a monstrous hybrid, part rooster and part serpent, hatched from an egg laid by a cockerel and incubated by a toad. It was confused with the cockatrice, a similar beast. And it became one of the most famous monsters of European folklore — a creature that could be defeated only with a mirror, a weasel, or the crow of a rooster.
Pliny’s Basilisk
The classical description of the basilisk comes from Pliny the Elder (first century CE), in his Natural History. Pliny wrote that the basilisk was found in the province of Cyrenaica (modern Libya). It was not more than twelve fingers long, and had a white spot on its head, like a diadem or crown. It did not move forward by coiling its body like other snakes, but proceeded upright, holding the middle of its body raised.
Its power was terrible. It drove away all other serpents with its hiss. It killed bushes not only by touch but by breathing on them, and scorched grass and split rocks. Pliny added that a man on horseback who killed a basilisk with a spear was himself killed, together with his horse, by the poison travelling up the spear.
But the basilisk had one enemy. Pliny wrote that the weasel could kill it. People threw weasels into the holes of basilisks, which were easily recognized because the ground around them was blasted. The weasel killed the basilisk with its smell — and died itself in the fight.
The Desert of Libya
The Roman poet Lucan, in his epic Pharsalia (first century CE), describes the serpents of the Libyan desert, which sprang from the drops of blood that fell from the severed head of Medusa as Perseus flew over the land. Among them was the basilisk, whose hissing terrified all other serpents, and which ruled the empty sands as a king.
The Glance That Kills
The basilisk’s most famous power, its deadly gaze, is not clearly found in Pliny, though he mentions that it could kill “by its look” in some readings. The idea became dominant in later writers. The medieval bestiaries described the basilisk as killing men simply by looking at them.
This belief was connected with the ancient and medieval theory of vision, which held that the eye emitted rays that touched the object seen. A creature with poisonous eyes could therefore poison anything it looked at.
The only defence was to turn its gaze back on itself. A basilisk that saw its own reflection in a mirror — or a polished shield — would die, killed by its own look. Travellers in the desert were advised to carry mirrors or crystal globes.
The Rooster and the Egg
In the Middle Ages, the basilisk took on a new form and a strange origin. According to the bestiaries and naturalists, a basilisk was hatched from an egg laid by a cockerel — an old rooster, seven or fourteen years old — and incubated by a toad or a serpent. The resulting creature had the head, legs, and comb of a rooster and the tail of a serpent, sometimes with wings.
This rooster-headed version was also called the cockatrice, and the two names were often used interchangeably. In English heraldry, the cockatrice became a distinct creature, a two-legged dragon with a rooster’s head, while the basilisk was sometimes shown with a second, dragon’s head at the end of its tail.
Defeating the Basilisk
Medieval lore listed several ways to defeat the monster:
- The weasel, immune to its gaze, which could attack it and kill it, eating rue to protect itself from the poison.
- The rooster, whose crowing killed the basilisk instantly. Travellers crossing deserts were said to carry roosters for protection.
- A mirror, to reflect its gaze back on itself.
Real Basilisk Trials
The belief in cockerel eggs was taken seriously. In 1474, in the Swiss city of Basel, a rooster was put on trial for the “heinous and unnatural crime” of laying an egg. It was found guilty and burned at the stake, along with the egg, to prevent a basilisk from hatching. (The “egg” was probably laid by a hen that had developed male characteristics due to a hormonal imbalance, a known condition in poultry.)
The Basilisk of Vienna
A famous Viennese legend tells that in 1212, a strange creature was found at the bottom of a well in the Schönlaterngasse, and its breath and stench made a baker’s apprentice faint. It was identified as a basilisk. A brave young man lowered a mirror into the well, and the basilisk, seeing itself, turned to stone. The well was filled in. The Basiliskenhaus at Schönlaterngasse 7 still carries a stone figure of the creature and an inscription recounting the story.
The Basilisk of Warsaw
In Warsaw, a legend says a basilisk lived in the cellars of an old house in the Old Town and killed two children. A condemned prisoner offered to kill it in exchange for his freedom. He wore a suit covered with mirrors and went into the cellar. The basilisk saw its own reflection and died.
What Was the Basilisk?
The basilisk of Pliny may have been inspired by real animals. The Egyptian cobra can spit venom that blinds its enemies; the hooded cobra rears up with its head raised; and the white markings on some species could have been taken for a crown. The mongoose, a known cobra-killer, may have inspired the weasel story. The horned viper of the Sahara, which moves by sidewinding, and hides in sand, might have contributed too.
The Basilisk in Modern Culture
The basilisk is famous today through J. K. Rowling’s Harry Potter and the Chamber of Secrets (1998), in which a giant basilisk lives beneath Hogwarts, killing with its gaze; those who see it only indirectly, through reflections or a camera, are merely petrified. The book draws closely on medieval lore: the basilisk was hatched from a chicken’s egg under a toad, spiders flee before it, and the crowing of a rooster is fatal to it.
The basilisk lizard of Central and South America, which can run across the surface of water on its hind legs (and so is nicknamed the “Jesus Christ lizard”), was named after the legendary creature because of the crest on its head.
Last reviewed: September 2026.