Harry Potter and the Chamber of Secrets' main mystery revolves around the students that are found petrified in the corridor of Hogwarts. The Basilisk was one of Harry's toughest creatures fought against, and since the boy's wizard knowledge was so limited at the time, he had no other option but to use his sharp wit to evade the monster until Fawkes came to his aid at the Chamber of Secrets. With the help of Ron and Hermione, Harry ensured Hogwarts wouldn't be closed and proved Hagrid's innocence, bringing peace back to the school and solving a decades-old mystery.
The events of Harry Potter and the Chamber of Secrets are directly linked to a tragedy that occurred during the 1942-1943 school year when a student was killed by a creature controlled by the heir of Slytherin. Hagrid was believed to be the culprit and his Acromantula friend, Aragog, the monster that terrorized Hogwarts. The monster's return in Harry's second school year is speculated when Mrs. Norris, Argus Flinch's beloved cat, is found petrified. When Hogwarts students are also found in this state, hints lead to a Basilisk: a gigantic snake who instantly kills anyone who stares directly into the creature's eyes.
Colin Creevey
Colin was one of the characters that suffered the most in Hogwarts, eventually meeting an unfortunate fate in the franchise's final film. Introduced in Harry Potter and the Chamber of Secrets, Colin and his camera became a single entity as the boy wandered the school grounds registering everything that crossed his path, especially Harry, whom the boy was obsessed with. His imprudent enthusiasm repelled friends, which explains why he was alone when the Basilisk found him.
Colin's love for taking pictures ended up saving his life. Since looking the Basilisk in the eye would've been fatal, only seeing the monster through his camera lens kept him alive. His petrified body was found holding tightly to his camera in the midst of taking a picture. It's easy to miss how brave Colin proved to be, but his attempt at taking a photo is part of figuring out the monster. He could've saved even more students if the Basilisk's power didn't cause the camera to malfunction, exploding in Dumbledore's hands.
Justin Finch-Fletchley
After Colin was found petrified, it was clear that Hogwarts was no longer safe, but the Basilisk's attacks impacted Harry directly when he stumbled upon two new victims: Justin Finch-Fletchley and the charismatic Gryffindor ghost Nearly-Headless Nick. Caught by Filch, the school's caretaker, while he inspected the petrified bodies, Harry became a major suspect in the mystery that haunted Hogwarts, strengthened by Filch's early suspicions about Harry, Ron, and Hermione finding his cat Mrs. Norris petrified next to a threatening message written with blood on the wall.
Justin Finch-Fletchley was a Hufflepuff student, and he would've certainly been killed by the Basilisk if it wasn't for Nearly-Headless Nick, who apparently stood in front of Justin, preventing him from staring directly into the monster's eyes. Nick had no choice but to face the Basilisk, but since he was already dead, he got petrified just like the others. Similarly to the previous Basilisk victims, Justin was a Muggle-born student. The character didn't have a major impact in the Harry Potter movies until Harry Potter and the Order of Phoenix when he joins Dumbledore's Army alongside Harry and his best allies.
Hermione Granger
Hermione's petrification delivers one major difference between the books and the movie since it omitted Penelope Clearwater's petrification. She is nowhere near Hermione when she is attacked at the library in the film. In the books, Hermione doesn't have anything with her to prevent the Basilik’s attack, so she desperately resorts to Clearwater's mirror and the two are petrified together, making it harder for Harry and Ron to dissect what really happened. In the movie, the mirror Hermione uses to protect herself from Basilisk belongs to herself, since Penelope isn't in the film, and she watches the creature's reflection to not look it in the eyes.
After going through the trouble of going into the Forbidden Forest and evading Aragog's spiders, the duo finds Hermione's note revealing the voice Harry was hearing at night was the Basilisk's. Hermione falling victim to the creature also shows how doomed Harry and Ron would be if they weren't friends with her. The petrification is vital to Hermione's character development and Voldemort's true nature. Aware that he's the Heir of Slytherin, Tom Riddle unleashes the Basilisk and vents his rage on the Hogwarts Muggle-borns because he thinks they are just like the Muggle father who deserted him and corrupted his childhood.
Myrtle Warren
The ending of Harry Potter and the Chamber of Secrets reveals important information about the events that took place when the chamber was first opened 50 years prior to Harry's second school year. It's important to notice that although the Moaning Myrtle isn't petrified in the movie, her death is vital to understanding how the basilisk acts. On Tom Riddle's command, Myrtle Warren was attacked by the Basilisk in the bathroom, looking into the creature's eyes and meeting a tragic fate. Harry's colleagues were lucky to only see the Basilik's reflection, thus only getting petrified and having a chance to be cured by the draught made by Mandrake roots.
In the present, Mrs. Norris saw the Basilisk's reflection through the water on the floor, Colin looked at the monster through his camera lens, Justin was lucky to have Nearly-Headless Nick in front of him, and Hermione used the mirror to avoid eye contact. A chain of events that happened by chance saved the lives of the students attacked by the Basilisk in Harry Potter and the Chamber of Secrets, but, unfortunately, Myrtle Warren wasn't lucky enough. Her death shocked the Hogwarts faculty and caused Hagrid to be expelled from the school, named by Riddle as the culprit after being caught with his Acromantula friend, Aragog.