The Serpent of Slytherin was a female Basilisk that was 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. That meant that despite her being a Snake, other Parselmouths (such as Harry Potter) had no control over her, though they still could 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 Hogwarts 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 1943, the Chamber of Secrets was opened by a Slytherin Fifth year, named Tom Riddle, who was able to control the Basilisk through his status as the Heir of Slytherin. Riddle unleashed the Basilisk on the school, with his goal of ridding the school of all of its Muggle-borns. All the victims were merely Petrified, except for a student named Myrtle, who was killed in the Girls' Bathroom on the Second Floor. A sink in that bathroom concealed the Entrance to the Chamber of Secrets. Those events were nearly the cause for the permanent closing of Hogwarts.
To avoid that 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 Professor, Albus Dumbledore became suspicious of Riddle, kept a very close watch over him his remaining years at Hogwarts, and thus prevented him from any further terror at the school, since Riddle feared discovery. Dumbledore also convinced Armando Dippet, who was Headmaster at that time, to allow Hagrid to stay at Hogwarts as Gamekeeper.
However, Riddle, who did not want his five years of hard work in finding out about the Chamber to go to waste, left behind a Diary, which he had purchased that same year, and contained a portion of his own Soul, in the hope 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]
Fifty years after Riddle's original attack on Hogwarts, the Basilisk was re-awakened by a shade of Riddle that was generated by a Horcrux that he had housed in his old diary. That shade possessed Ginny Weasley after Lucius Malfoy had slipped the diary into her cauldron during a confrontation at Flourish and Blotts, as part of his plan to discredit her father, Arthur Weasley. 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, Nearly Headless Nick, 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.
Later in their search, Hermione Granger became one of the Basilisk's victims, but she had already managed to get some information on the Basilisk for Harry and Ron Weasley, 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 was held by Riddle. After he was separated from Ron and the self-Obliviated Lockhart, a battle commenced between Harry 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]
During the battle between Harry 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 the Statue of Slytherin, 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 felt the poison spreading. Harry was only saved by Fawkes' Tears, and subsequently used the fang (on which his arm had been impaled) to destroy Riddle's Diary, which he later discovered was one of Voldemort's Seven Horcruxes.
By 1998, the Basilisk's body was fully decomposed, which left just a skeleton. Another one of the Basilisk's Fangs was used once again by Hermione 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]
The Basilisk was an extremely powerful and dangerous creature. A horrifying monster with dark green scales, that 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 resulted in death, while an indirect look only resulted 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, ceased to age as long as she remained asleep.
Salazar Slytherin's Basilisk only listened to the Heir of Slytherin, Tom Riddle (Voldemort), regardless of Harry 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 while 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 ferociously continued her goals no matter how many obstacles that she encountered.
Known Victims of the Basilisk
- "Come... Come to me... let me rip you... let me tear you..."
- —The Basilisk calling to its victims (Parseltongue, only heard by Harry)[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 Riddle'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
- At no point in the series was it explained how the Basilisk sustained itself. While 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. That was 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 did not get pierced by the Basilisk's Fang and instead pulled it out of the dead Basilisk's mouth. Also, the Basilisk noticed Harry when Ginny screamed at one of his disembodied eyes. A third difference was that the Basilisk had a scarlet plume on its head, and thus its gender was male. Additionally, Ginny helped Harry during the battle as opposed to unconscious the whole time.
- Ironically, the Basilisk that Voldemort had plotted to use to purge Hogwarts of Muggle-borns and Harry was used against him by having her venom destroy most of his Horcruxes, which led to his Final Downfall and Death. Even more ironic, Voldemort's Horcruxes that were not destroyed by the Basilisk's venom were each destroyed by Vincent Crabbe 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 that three Muggle-borns were attacked instead of four like in the book.
- 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 five 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.
- 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, which implied that either it had one and he simply didn't see it, or that the Basilisk was female. That was further supported by Pottermore, which depicted the snake with a distinct lack of a crown, red or otherwise.
- In the Video Game adaptations of Chamber of Secrets, the Basilisk tended 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 dodged. After failing to kill Harry from the mouth of Slytherin's Statue, the Basilisk popped up from the grating in the floor to try and bite or spray Harry. When she was killed, the Basilisk simply fell on Riddle's Diary, and presumably buried her fangs into the book and destroyed it. In the Game Boy Color Version however, Harry instead used the Sword of Gryffindor itself to destroy the diary.
- Also, in the console versions, the Basilisk was grey. To defeat her, Harry must fire a beam of light at the Basilisk's mouth/head when her weak-point was exposed in order to zap her (in the PS2 Version, it was a black diamond-shape on her neck, while in the Xbox and Gamecube Versions, it was her throat). Damaging it properly just once caused Harry to drop the Sword as it flung away to certain parts of the arena, and Harry rushed back up to it, picked it up again, and rinsed and repeated.
- In the Game Boy Advanced Version, Harry only cast Spells at the Basilisk and the Sword was not mentioned at all.
- In the PS1 Version, the Basilisk was coloured blue, while she must be defeated in two phases akin to the PC Version; Harry first cast Spells into her mouth, then in the second phase, used the Sword to direct venomous-laser beams that were 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 was the only known death in the series that occurred in 1993 (unless one counted 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 was possible that said horn came from that Basilisk.
- It was 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 mentioned that there were no Basilisk sightings in Great Britain for centuries. It is also possible that Magizoologists disregarded this Basilisk's existence for having been artifically created by Salazar Slytherin, rather than a wild specime who intentionally migrated to Britain.
- Harry Potter and the Chamber of Secrets (First appearance)
- Harry Potter and the Chamber of Secrets (film)
- Harry Potter and the Chamber of Secrets (video game)
- Harry Potter and the Prisoner of Azkaban (Mentioned only)
- Harry Potter and the Goblet of Fire (Mentioned only)
- Harry Potter and the Order of the Phoenix (Mentioned only)
- Harry Potter and the Order of the Phoenix (film) (Mentioned only)
- Harry Potter and the Order of the Phoenix (video game) (Mentioned only)
- Harry Potter and the Half-Blood Prince (Mentioned only)
- Harry Potter and the Deathly Hallows (Mentioned only)
- Harry Potter and the Deathly Hallows: Part 1 (Mentioned only)
- Harry Potter and the Deathly Hallows: Part 1 (video game) (Mentioned only)
- Harry Potter and the Deathly Hallows: Part 2 (Appears as a corpse)
- LEGO Harry Potter
- LEGO Harry Potter: Years 1-4
- LEGO Harry Potter: Years 5-7 (Appears as a corpse)
- LEGO Creator: Harry Potter and the Chamber of Secrets
- LEGO Harry Potter
- Harry Potter Trading Card Game
- Harry Potter for Kinect
- Harry Potter: The Creature Vault