|Others||King of Serpents|
|Average length||50 feet|
|Lifespan||900 - 1000 years|
|Behind the Scenes|
|Created by||J. K. Rowling|
|Performed by||Randy Thoms, horse, elephant, and tiger vocals|
The Basilisk is a giant serpent, also known as the King of Serpents. It is a creature bred by Dark Wizards. Herpo the Foul was the first to breed a Basilisk; he accomplished this by hatching a chicken egg beneath a toad which resulted in the creature known as a Basilisk. Basilisk breeding was banned in Medieval times. However, the practice can be hidden when the Department for Regulation and Control of Magical Creatures comes to check by simply removing the egg from the toad.
The Basilisk can grow up to fifty feet in length, and is a dark green colour with large yellow eyes. These eyes have the power to instantly kill anyone who looks into them. Basilisk skin is armoured like that of a dragon's, which deflects spells cast upon it. The Basilisk sheds its skin at intervals, like all other snakes, when it grows.
Basilisks can live a natural life of at least nine hundred years, though Salazar Slytherin's Basilisk lived for approximately a thousand years. This is accomplished by using Parseltongue to put the creature into a deep sleep that prevents it from aging, similar to suspended animation. Their mortal weakness is the crowing of a rooster. Basilisks feed off vertebrate animals. The male can be distinguished from the female by a single scarlet plume on its head.
When a victim looks indirectly at the Basilisk's eyes, such as its reflection, they will merely become Petrified, as was the case with Hermione Granger and Colin Creevey, however Myrtle (commonly known as Moaning Myrtle) was not so fortunate, and looked directly into the Basilisk's eyes, which resulted in her dying immediately. Another way of surviving a Basilisk's gaze is by seeing it through another object. Another example mentioned above was when Colin Creevey saw it through his camera, resulting in his petrification and his camera lens becoming melted. Justin Finch-Fletchley saw the Basilisk through the translucent Nearly-Headless-Nick, and both were petrified. Sir Nicholas, being a ghost, was already dead; as such, he only became Petrified as well, although he did look at the beast's eyes directly. This petrification seems quite powerful, as even the Elder Wand-wielding Albus Dumbledore concluded that the only way to reverse the effect was through the use of Mandrake Restorative Draughts.
Phoenixes are immune to this deadly gaze, and spiders, such as Aragog and his ever-growing clan, are terrified of the Basilisk, and describe it as their enemy, refusing to even speak of it or mention its name.
Basilisk venom is an extremely poisonous substance that only has one known cure: phoenix tears. Basilisk venom is so powerful that it can kill a person within minutes, making the person drowsy and blurry-visioned before they die. It has a very long lasting effect which still remains potent even up to five years or more after the snake has died. It can also damage inanimate objects so thoroughly that they are impossible to restore, and thus it is one of the few substances powerful enough to destroy a Horcrux.
When Harry Potter slew Salazar Slytherin's Basilisk with Godric Gryffindor's Sword in 1992, the sword became imbued with the basilisk's venom, giving it the ability to destroy a Horcrux.
A Basilisk egg is the egg of said creature. They are chicken eggs hatched beneath a toad, thus creating the deadly King of Serpents. This method was first discovered by Herpo the Foul, in Ancient Greece, and has been banned since medieval times. The Ministry of Magic has said that all chicken coops in the Wizarding world are subject to police inspection in order to thwart Basilisk breeding.
- According to Igor Karkaroff, Alastor Moody has smashed apart a birthday present that he thought in paranoia was a cleverly disguised basilisk egg before finding out it was a carriage clock.
- The basilisk is often confused with the cockatrice, but the basilisk is born from a chicken’s egg hatched beneath a toad, while the cockatrice is hatched by a chicken's egg incubated by a serpent. The cockatrice is also usually depicted with wings, while the basilisk is not. Due to this, it can be assumed that J.K. Rowling either had the two confused, or decided to combine the two. A cockatrice is the product of an egg laid by a cock (a male chicken) and incubated by a toad or a snake, can kill by looking at a person, touching them, or sometimes breathing on them, and was slain instantly by a rooster's crow.
- Although an average basilisk is said to have an average lifespan of 900 years Salazar Slytherin's Basilisk lived for approximately 1000 years, being there since Slytherin built the Chamber of Secrets around that time.
- In LEGO Harry Potter: Years 1-4, the basilisk is male because it has a red plume on its head.
- Newt Scamander stated in Fantastic Beasts and Where to Find Them that there have been no recorded sightings of Basilisks in Britain for the last 400 years. Harry Potter wrote in his copy of the book "that's what you think".
- Wearing glasses will not protect a person from the fatal effect of the basilisk's stare, because glasses still allow one's line of vision to connect directly and clearly with the serpent's eyes, unlike looking in a mirror or through a camera.
- It has been theorized that spiders fear basilisks because arachnids can see 360-degrees around them and cannot shut their eyes, leaving them extremely vulnerable to the monster's killing gaze.
- In the film adaptation of Harry Potter and the Chamber of Secrets, Harry watches the basilisk by its shadow on the floor.
- It is unknown why there are male and female basilisks, as they are produced by a chicken's egg hatched by a toad. However, it's possible that, unlike real-world hybrids, basilisks are capable of reproduction as Moody had a present that "he thought was a well-disguised basilisk egg", suggesting that basilisks can lay eggs.
- In the film adaptation for Harry Potter and the Chamber of Secrets, the Basilisk is shown to hear Harry Potter, something that Tom Riddle's memory also points out. However, snakes lack ears and can only detect things approaching by feeling vibrations. In the book, Riddle instead only tells the Basilisk to smell Harry Potter.