Serpent of Slytherin

Salazar Slytherin created the Chamber of Secrets at Hogwarts, and inside this Chamber was placed a Basilisk that could only be controlled by his true heir (a Parselmouth). In the early 1940's, the Chamber of Secrets was opened by a Slytherin fifth-year, Tom Riddle, who was able to control the creature through this method. Riddle unleashed the Basilisk on the school, his goal to kill the Muggle-born students. All of the victims were merely petrified, except for a student named Myrtle who was killed in the girls bathroom. This bathroom was also the entrance to the Chamber of Secrets. These events were nearly the cause for permanent closing of Hogwarts. To avoid this fate for Hogwarts, Riddle blamed Gryffindor third-year Rubeus Hagrid for all the events, claiming the monster at fault was his pet Acromantula. Hagrid was expelled, and the attacks stopped. However, Headmaster Albus Dumbledore became suspicious of Riddle and thus prevented him from further terrorizing the school from fear of discovery.

During the battle between Harry Potter and the Basilisk, Fawkes was able to blind the Basilisk and buy Harry some time. During that period of hiding, Harry obtained the Godric Gryffindor's sword and stabbed the Basilisk through the roof of its mouth. Harry subsequently used one of the creature's fangs to destroy Tom Riddle's diary, which was being used to connect Voldemort's fragile soul to the material world.

Another one of the basilisk's fangs was used again at a later time to destroy a similar object, Helga Hufflepuff's Cup.

Victims
The following list shows all known Basilisk victims both killed and petrified.

Killed Petrified
 * Myrtle
 * Mrs. Norris
 * Justin Finch-Fletchley
 * Nearly-Headless Nick
 * Colin Creevey
 * Hermione Granger
 * Penelope Clearwater

Appearances

 * Harry Potter and the Chamber of Secrets
 * Harry Potter and the Chamber of Secrets (film)
 * Harry Potter and the Chamber of Secrets (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 Half-Blood Prince
 * Harry Potter and the Deathly Hallows