Serpent of Slytherin

"...That is believed to be some sort of monster..."

- Professor Binns on the Chamber of Secrets' occupant

The Serpent of Slytherin was a female basilisk placed by Salazar Slytherin inside the Chamber of Secrets at Hogwarts School of Witchcraft and Wizardry. The basilisk could only be controlled by Slytherin's one true heir, Tom Riddle. This means that despite her being a snake, other Parselmouths (such as Harry Potter) have no control over her, though they could still understand her.

Birth and early years
Salazar Slytherin's basilisk was born in the Chamber, 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 hopes that one day his true heir would unleash her to purge all he deemed unworthy to study magic.

First opening of the Chamber of Secrets
In the early 1940s, the Chamber of Secrets was opened by a Slytherin fifth year, 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, his goal being to rid the school of Muggle-born students. All the victims were merely Petrified, except for a student named Myrtle, who was killed in the girls' bathroom on the first 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 he had to a home, Riddle framed Gryffindor third year Rubeus Hagrid for all the events, claiming 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 thus prevented him from further terrorising the school, since Riddle now 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, containing a portion of his 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
Fifty years after Tom Riddle's original attack on Hogwarts, the basilisk was re-awakened by a shade of Riddle generated by a Horcrux he had housed in his old diary. This shade possessed Ginny Weasley after Lucius Malfoy 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 killed the Hogwarts roosters to prevent them being used against the basilisk, no deaths occurred (Riddle implies that this was because his obsession with exacting revenge on Harry Potter overrided even his desire to carry out his role in purging 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 it 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 in a petrified-like state. Using his own ability as a Parselmouth, Harry was able to hear the basilisk and attemped to find her. 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.



During the battle between Harry Potter and the basilisk, Dumbledore's phoenix Fawkes was able to blind the basilisk, allowing Harry to fight the basilisk without the fear of being killed instantly by its 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 it to the top of Slytherin's statue, where he slashed at the evil creature fiercely. The basilisk lunged at him, knocking Harry over, but just as it lunged again to kill him, Harry grabbed the sword and stabbed the basilisk through the roof of its mouth, mortally wounding it. Unfortunately, one of its 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 it ultimately lost its ability to live and its massive weight finally brought it crashing to the floor. Harry yanked the fang out, but knew it was too late: he could feel 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.

Post-mortem
By 1998 the basilisk's body had fully decomposed, leaving 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 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.

Traits


"Parseltongue won't save you now, Potter, it only obeys me!"

- Riddle's fragmented soul on the serpent's allegiance. A horrifying monster with dark green scales, this creature was immensely large and had deep yellow eyes. It possessed great strength and was resistant to a majority of spells, and as a basilisk, it could kill with a gaze, and petrify with an indirect look. In addition, its fangs were so venomous, it could kill any living creatures it pierced within minutes, and were capable of destroying Horcruxes; the venom's potency remained even after five years of its death. Even when blinded (which took away its deadly gaze), it could still sense its prey through smell and sound.

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

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 it in the Chamber of Secrets. It is possible that the basilisk was trained, enchanted, or persuaded to obey only the Heir of Slytherin, and not all Parselmouths.

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

Killed

 * Moaning Myrtle
 * Postmortem: fangs and venom destroyed two pieces of Tom Riddle's soul (in Tom Riddle's Diary in 1993 and Helga Hufflepuff's Cup in 1998.)
 * Indirectly: Godric Gryffindor's Sword which is imbibed with a Basilisk's venom, destroyed Salazar Slytherin's Locket and Marvolo Gaunt's Ring, both of which 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.

Petrified

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

Injuries

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

Behind the scenes

 * 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 screams at one of his disembodied eyes. A third difference is that the basilisk has a scarlet plume on its head, thus its gender is male. Additionally, Ginny helps Harry during the battle as opposed to being unconscious the whole time.
 * Ironically, the serpent that Voldemort plotted to use to purge the school of muggle-borns and Harry Potter was used against him by having its venom and fangs used to destroy most of his horcruxes, which led to his final downfall.
 * Penelope Clearwater is 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 is 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.
 * In Harry Potter and the Deathly Hallows: Part 2, when Ron and Hermione enter the Chamber of Secrets, the skeleton of the basilisk is still there, but appears to be in a different spot than where Harry killed it earlier. 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 seems to be female: when Harry first sees it he describes it as "vivid, poisonous green" but makes 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 is further supported by Pottermore, which depicts the snake with a distinct lack of a crown, red or otherwise.
 * In the video game adaptations of Chamber of Secrets, the serpent tends to be different colors. In the PC version (as well as the GBC version), it is not green but purple, and attacks 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 pops from grating in the floor to try and bite or spray Harry. When it is killed, it simply falls on Riddle's diary, presumably burying it's fangs in the book and destroying it.
 * Also, in the console versions the serpent is gray. And to defeat it, Harry must fire a beam of light at the snake's mouth/head when its weakpoint is exposed in order to zap it. 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 is not mentioned at all.
 * A giant snake used as a boss battle in  uses 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).

Appearances

 * Harry Potter and the Chamber of Secrets
 * Harry Potter and the Chamber of Secrets (film)
 * Harry Potter and the Chamber of Secrets (video game)
 * Harry Potter and the Prisoner of Azkaban
 * Harry Potter and the Goblet of Fire
 * Harry Potter and the Order of the Phoenix
 * Harry Potter and the Order of the Phoenix (film)
 * Harry Potter and the Order of the Phoenix (video game)
 * Harry Potter and the Half-Blood Prince
 * Harry Potter and the Deathly Hallows
 * Harry Potter and the Deathly Hallows: Part 1
 * Harry Potter and the Deathly Hallows: Part 1 (video game)
 * Harry Potter and the Deathly Hallows: Part 2
 * LEGO Harry Potter: Characters of the Magical World
 * LEGO Harry Potter: Years 1-4
 * LEGO Harry Potter: Years 5-7 
 * LEGO Creator: Harry Potter and the Chamber of Secrets
 * Harry Potter LEGO Sets
 * Harry Potter Trading Card Game
 * Pottermore
 * Harry Potter for Kinect

Notes and references
Bazyliszek Salazara Slytherina Basilisco di Salazar Serpeverde Василиск Салазара Слизерина