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Serpent of Slytherin

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"Well the Chamber is said to be home to something that only the Heir of Slytherin can control. It is said to be the home... of a monster."
McGonagall on the Chamber of Secrets' occupant[src]

The Serpent of Slytherin[2] was a female Basilisk placed by Salazar Slytherin as the only resident of the Chamber of Secrets at Hogwarts School of Witchcraft and Wizardry: The Basilisk could only be controlled by the heir of Slytherin, Tom Riddle. This meant that despite her being a Snake, other Parselmouths (such as Harry Potter) had no control over her, though they could still understand her.


Birth and Early Years

Salazar Slytherin's Basilisk was born in the Chamber of Secrets, as revealed by Aragog. Slytherin, in his spite of his fellow founders' acceptance of Muggle-borns into the school, left a Basilisk deep in the Chamber, in the hope that one day his true heir would unleash her to purge all that he deemed were unworthy to study magic at Hogwarts.

First opening of the Chamber of Secrets

"But I know one thing — last time the Chamber of Secrets was opened, a Mudblood died."
—Draco Malfoy regarding the first opening[src]

In the early 1940s, the Chamber of Secrets was opened by a Slytherin fifth year, named Tom Marvolo Riddle, who was able to control the creature through his status as the Heir of Slytherin. Riddle unleashed the Basilisk on the school, with his goal of being able to rid the school of all of its Muggle-born students. All the victims were merely Petrified, except for a student named Myrtle, who was killed in the Girl's Bathroom on the second floor. A sink in this bathroom concealed the Entrance to the Chamber of Secrets. These events were nearly the cause for the permanent closing of Hogwarts.

To avoid this undesirable consequence for Hogwarts, which was the closest thing that he had to a home, Riddle framed Gryffindor third year, Rubeus Hagrid for all the events, and claimed that Hagrid's pet Acromantula, Aragog was responsible for the attacks. Hagrid was expelled, and the attacks stopped. However, Transfiguration teacher, Albus Dumbledore became suspicious of Riddle and kept a very close watch over him his remaining years at Hogwarts, and thus prevented him from further terrorising the school, since Riddle then feared discovery. Dumbledore also convinced Professor Armando Dippet, who was Headmaster at that time, to allow Hagrid to stay at Hogwarts as Gamekeeper.

However, Riddle, not wanting his five years of hard work in finding out about the Chamber go to waste, left behind his Diary, which he had purchased that same year, and contained a portion of his own Soul, in the hopes that one day it would allow him to, through possession of an unwitting host, reopen the Chamber and reawaken the Basilisk.

Second opening of the Chamber of Secrets

"The Chamber of Secrets has been opened. Enemies of the heir... beware"
—The writing on the wall[src]

The writing on the wall, an indication that the Chamber has been opended once more

Fifty years after Tom Riddle's original attack on Hogwarts, the Basilisk was re-awakened by a shade of Riddle that was generated by a Horcrux he had housed in his old diary. This shade possessed Ginny Weasley after Lucius Malfoy had slipped the diary into her cauldron during a confrontation in Flourish & Blotts, as part of his plan to discredit her father. However, although Riddle/Ginny had killed all of the Hogwarts roosters to prevent them from being used against the Basilisk, no deaths occurred (Riddle implied that this was because of his obsession with exacting revenge on Harry Potter overrode even his desire to carry out his role in purging all of the Muggle-borns). The Basilisk managed only to petrify a few Muggle-born students and Argus Filch's cat, Mrs Norris, since all of them only saw the snake's reflection or saw her through something, rather than looking upon the snake directly. In addition, a Ghost received the full force of the Basilisk's gaze, but as he was already dead, he was merely put into a Petrified-like state. Using his own ability as a Parselmouth, Harry was able to hear the Basilisk and attempted to find her.


Hermione and the other petrified victims

Later in their search, Hermione became one of the Basilisk's victims, but she had already managed to get some information on the Basilisk for Harry and Ron, information which they found still clutched in her petrified hand. Harry and Ron (accompanied by a reluctant Gilderoy Lockhart) entered the Chamber of Secrets, where Ginny Weasley was being held by Tom Riddle. After being separated from Ron and the self-Obliviated Lockhart, a battle commenced between Harry Potter and the Basilisk.

Battle with Harry Potter and death

"Speak to me, Slytherin, greatest of the Hogwarts four!"
—Riddle's fragmented soul summoning the serpent[src]
Tumblr n29413O6t71rzvuwqo7 r1 250

Harry kills Slytherin's Basilisk with Godric Gyffindor's Sword in the Chamber of Secrets

During the Battle between Harry Potter and the Basilisk, Dumbledore's phoenix, Fawkes was able to blind the Basilisk, which allowed Harry to fight her without the fear of being killed instantly by her gaze. After a period of hiding, Harry obtained Godric Gryffindor's Sword from the Sorting Hat, which had been brought to him by Fawkes. Harry lured her to the top of Slytherin's Statue, where he slashed at the evil creature fiercely. The Basilisk lunged at him, and knocked Harry over, but just as she lunged again to kill him, Harry grabbed the sword and stabbed the Basilisk through the roof of her mouth, and mortally wounded her. Unfortunately, one of her fangs pierced Harry in his sword arm as a result of the struggle, and splintered off as the Basilisk pulled away and flailed around in agony before she ultimately lost her ability to live and her massive weight finally brought her crashing down to the floor. Harry yanked the fang out, but knew it was too late: he fell the poison spreading. Harry was only saved by Fawkes' tears, and subsequently used the fang (that his arm had been impaled on) to destroy Tom Riddle's Diary, which he would later discover was one of Voldemort's seven Horcruxes.


Basilisk skeleton

The Basilisk's skeleton in the Chamber of Secrets in 1998

By 1998, the Basilisk's body had fully decomposed, which left just a skeleton. Another one of the Basilisk's Fangs was used once again by Hermione Granger to destroy another Horcrux, Helga Hufflepuff's Cup. The first fang's venom, which was absorbed by the sword that slew it due to its taking in only that which made it stronger, allowed it to destroy Salazar Slytherin's Locket. While the sword slew Nagini, due to her being a living creature, it's unknown whether or not any sword would have done the job.


"Parseltongue won't save you now, Potter, it only obeys me!"
—Riddle's fragmented soul on the serpent's allegiance[src]
Slytherin's basilisk

The Basilisk lunges at Harry Potter in the Chamber of Secrets

The Basilisk was an extremely powerful and dangerous creature. A horrifying monster with dark green scales, this creature was a violent and bloodthirsty beast of titanic size, and had deep yellow eyes. She possessed incredible strength and durability (She survived smashing her head against thick stone) and was resistant to a majority of spells.

Direct contact with her gaze results in death, while an indirect look only results in petrification, similar to the Medusa stare. In addition, her fangs were so venomous, she could kill any living creatures that she pierced within minutes, and were capable of destroying Horcruxes; the venom's potency remained even after five years of her death. Even when blinded (which took away her deadly gaze), she could still sense her prey through smell and sound, and proved to be extremely dangerous, if not more so, despite her disadvantage.

The Basilisk could breathe while submerged underwater, squeeze through the piping network of the school to go about undetected, and by entering a deep sleep, she ceased to age as long as she remained asleep.

Salazar Slytherin's Basilisk would only listen to the true Heir of Slytherin, Tom Marvolo Riddle (also known as Lord Voldemort), regardless of Harry Potter being able to understand and speak Parseltongue to her in the Chamber of Secrets. It was possible that the Basilisk was trained, enchanted, or persuaded to obey only the Heir of Slytherin, and not all Parselmouths.

The Basilisk's personality was not particularly complicated. She was extremely bloodthirsty and sadistic, judging by the things she said whilst Harry listened to her attacking her victims. She was blindly and unshakably devoted to the heir of Slytherin, for aforementioned reasons. She had nerves of steel, and would ferociously continue her goals no matter how many obstacles she encountered.

Known Victims of the Basilisk

"Come... Come to me... let me rip you... let me tear you..."
—The Basilisk calling to it's victims (in Parseltongue, only heard by Harry Potter)[src]

The following list shows all known Basilisk victims both killed, Petrified, and otherwise harmed by the monster.


  • Myrtle Warren
  • Postmortem: fangs and venom destroyed two pieces of Tom Riddle's Soul (Tom Riddle's Diary in 1993, and Helga Hufflepuff's Cup in 1998.)
  • Indirectly: Godric Gryffindor's Sword which was imbibed with the Basilisk's venom, destroyed Salazar Slytherin's Locket and Marvolo Gaunt's Ring, both of which also contained a piece of Tom's soul.
    • The sword also slew Nagini, though the venom may not have been necessary to release the soul, due to the instability of living Horcruxes.


  • Several unknown students during 1943
  • Mrs Norris (saw her reflection in puddle of water)
  • Colin Creevey (saw her through the lens of his camera)
  • Justin Finch-Fletchley (saw her through Nearly Headless Nick)
  • Nearly Headless Nick (made eye contact, but was a ghost, and could not die again)
  • Hermione Granger (saw her in Penelope's mirror)
  • Penelope Clearwater (saw her in her mirror)


  • Harry Potter (her fang went into Harry's arm, who would have died if not healed by Fawkes tears)

Behind the scenes

Basilisk LEGO

The Basilisk in LEGO form

  • At no point in the series is it explained how the basilisk sustained itself. While the acromantulas feared it they never described the serpent preying on them, and despite her bloodthirsty nature, the basilisk never fed on any of its victims. This is especially noteworthy because on the night it attacked Mrs. Norris it said "So hungry for so long".
  • In LEGO Harry Potter: Years 1-4, Harry does not get pierced by the Basilisk's Fang and instead pulls it out of the dead Basilisk's mouth. Also, the Basilisk notices Harry when Ginny screamed at one of his disembodied eyes. A third difference was that the Basilisk had a scarlet plume on its head, thus its gender was male. Additionally, Ginny helped Harry during the battle as opposed to being unconscious the whole time.
  • Ironically, the Basilisk that Voldemort plotted to use to purge Hogwarts of Muggle-borns and Harry Potter was used against him by having her venom used to destroy most of his Horcruxes, which led to his final downfall and death. Even more ironic, his Horcruxes that were not destroyed by the Basilisk's venom were each destroyed by one of his Death Eaters and by Voldemort himself.
  • Penelope Clearwater was the only victim of the 1992–1993 school year incident who was not a victim of Slytherin's Basilisk in the film adaptation of Harry Potter and the Chamber of Secrets. Still, there was a mirror next to Hermione's bed, but it was never mentioned that Penelope was with Hermione. Furthermore, in the film, Cornelius Fudge claimed three Muggle-borns were attacked instead of four as in the novel.

The mouth of the Basilisk (left Year 7, right Year 2)

  • In Harry Potter and the Deathly Hallows: Part 2, when Ron and Hermione entered the Chamber of Secrets, the skeleton of the Basilisk was still there, but appeared to be in a different spot than where Harry had killed her six years ago. However, it's common for decaying bodies to experience changes as they decompose, such as their bones parting or closing together because of the forces breaking down the body. A contributing factor may have been the rats in the Chamber of Secrets, which may have fed on the defeated serpent some time after its death. Also, in the film, the fang was used to destroy an additional Horcrux, Rowena Ravenclaw's Diadem.
  • In recalling his father reading the first two Harry Potter books to him, Daniel Radcliffe stated that his father had a great voice for the Basilisk. He suggested his father to Director, Chris Columbus, and his father was mortified.[3]
  • Various medias have shown both the male and female depictions of the species for Slytherin's Basilisk. In the books it seemed to be female: when Harry first saw it, he described it as "vivid, poisonous green" but made no mention of a red crown, implying that either it had one and he simply didn't see it, or that the Basilisk was female. This was further supported by Pottermore, which depicted the snake with a distinct lack of a crown, red or otherwise.
Screenshot 438

Harry Potter and the Chamber of Secrets (GBC)

  • In the video game adaptations of Chamber of Secrets, the serpent tends to be depicted in colours. In the PC version (as well as the GBC version), she was not green but purple, and attacked by spraying a purple stream of venom which Harry must dodge. After failing to kill Harry from the mouth of Slytherin's Statue, the snake popped up from the grating in the floor to try and bite or spray Harry. When she was killed, she simply fell on Riddle's Diary, and presumably buried her fangs into the book and destroyed it. In the GBC version however, Harry instead uses the sword itself to destroy the diary.
    • Also, in the console versions, the serpent was grey. To defeat her, Harry must fire a beam of light at the snake's mouth/head when her weakpoint was exposed in order to zap her (in the PS2 version, it is a black diamond-shape on her neck, while in the Xbox and Gamecube versions it is her throat). Damaging it properly just once will cause Harry to drop the sword as it flings away to certain parts of the arena, and Harry much rush back up to it and pick it up again to rinse and repeat.
    • In the GBA version, Harry only casts spells at the Basilisk and the sword was not mentioned at all.
    • Meanwhile in the PS1 version, the snake is coloured blue, while she must be defeated in two phases akin to the PC version; only Harry first must cast spells into her mouth, then in the second phase must use the sword to direct venomous-laser beams fired from her fangs back at the said fangs.
  • A giant snake that was used as a boss battle in LEGO Indiana Jones: The Original Adventures used the same model as the Serpent of Slytherin from the LEGO Harry Potter sets (though not the more detailed model used in LEGO Harry Potter: Years 1-4).
  • The Basilisk's death is the only known death in the series that occurs in year 1993 (unless one counts the destruction of the diary horcrux as a death, in which case there were two deaths).
  • As Salazar Slytherin's wand was made of Basilisk horn, it is possible that said horn came from this basilisk.
  • It is possible that the fact that Salazar Slytherin's monster was a Basilisk was not made public even after its death, given Newt Scamander's 2017 edition of Fantastic Beasts and Where to Find them still mentions that there have been no Basilisk sightings in Great Britain for centuries.


Screenshot 1175

Boss portrait in the Chamber of Secrets video game (PS2 version)

Notes and references

  1. Fantastic Beasts and Where to Find Them -- male basilisks have a scarlet plume upon their head.
  2. Harry Potter and the Chamber of Secrets, Chapter 17 (The Heir of Slytherin)
  3. Harry Potter and the Deathly Hallows: Part 2, Blu-ray bonus - A Conversation with J.K. Rowling and Daniel Radcliffe

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