The Dark Lord — aka Voldemort — created seven Horcruxes in an attempt to sustain immortality. But, as you may have heard, Voldemort's plan ultimately failed. Harry Potter and co. found and destroyed all of his Horcruxes.
In the movies, the Horcruxes are destroyed in these ways: The killing curse — “Avada Kedavra.” Fiendfyre — a curse that creates powerful and magical flames. Godric Gryffindor's sword — one that was pulled from the Sorting Hat.
Albus Dumbledore, the man who discovered Voldemort's Horcrux plan and deigned to destroy them, long suspected that many of said Horcruxes would hold some sort of historical or personal value to the Dark wizard, and that was extremely true of this Horcrux, a family heirloom, and transformed by murdering his own father.
In a tense moment, Nagini cornered Ron and Hermione and was about to strike when Neville beheaded her. Neville destroyed the final Horcrux and proved himself a worthy wizard in the process. In the closing moments of The Deathly Hallows: Part 2, Voldemort, is defeated and Hogwarts is deemed safe again.
Hermione Granger and Ron Weasley destroy the Hufflepuff's cup Horcrux inside the Chamber of Secrets—Hermione giving it the fatal blow with a basilisk fang.
Voldemort intentionally made six Horcruxes, but when he used Avada Kedavra on Harry, he unintentionally created a seventh Horcrux. Instead of dying, Lily's love for Harry created a counter 'curse' known as Sacrificial Protection and saved Harry.
Quirrell is, in effect, turned into a temporary Horcrux by Voldemort. He is greatly depleted by the physical strain of fighting the far stronger, evil soul inside him.
The cup, which was made a Horcrux with Hepzibah's death, was left with Bellatrix Lestrange who kept it at Gringotts.
Due to his humiliation in the Triwizard Tournament, Cedric eventually becomes a Death Eater and kills Neville Longbottom. Due to Neville's death, the final Horcrux Nagini was never destroyed, and as a result Voldemort is never defeated, kills Harry and takes over the Wizarding World.
In an interview, J.K. Rowling revealed that it was the murder of Bertha Jorkins that made Nagini a Horcrux. After Voldemort discovered his Horcruxes were in danger, Nagini was magically protected, described as being encased in a 'starry, translucent sphere'.
A Horcrux is considered destroyed when it's damaged beyond repair. In the case of living Horcruxes, “damaged beyond repair” would mean dead. So, yes, Avada Kedavra can destroy a Horcrux, as long as that Horcrux is a living being.
He finds out for sure immediately after Nagini's attack on Arthur Weasley. This night is significant in many ways. While Harry sleeps, he enters Nagini's mind.
This theory suggests that each time he created a new Horcrux, that specific Horcrux diminished a part of his soul. Thus, his nose began to sink in, eventually disappearing altogether. Due to his tampering with dark magic, his human appearance evolved into a more snake-like state.
Horcrux: Quirinus Quirrell
This Hogwarts professor literally became a Horcrux when Voldemort decided to share his body. Quirrell was unable to resist Voldemort's will and was forced to do his evil deeds.
Upon learning of the diadem's location, Riddle travelled to the Albanian forest shortly after he left school and acquired the diadem. He transformed it into his fifth Horcrux by killing an Albanian peasant, and later chose to return it to the very place it had originated from: Hogwarts.
After graduating from Hogwarts in 1945, Tom Riddle goes down a dark path and becomes Lord Voldemort after he vanishes for a little while. When he comes back, he decides that his name should be Lord Voldemort.
Cedric and Harry completed the Third Task together. Both took hold of the Triwizard Cup, which transported them to the Little Hangleton graveyard, where Cedric was murdered by Peter Pettigrew with the Killing Curse, on the orders of Lord Voldemort.
It was a twist of extremely cruel fate that for befriending Harry rather than going against him, Cedric lost his life. Even worse, it was through a combination of Cedric's nobility and Harry's fairness that led the pair to the trap where he died.
In 1998, Fred participated in the Battle of Hogwarts, defending the castle's passageways with his twin. While fighting alongside his brother, Percy, he was killed in an explosion possibly caused by Death Eater Augustus Rookwood.
In Deathly Hallows, Hermione faced a real test of her physical and psychological stamina. After being on the run from a bunch of Snatchers, the gang were taken to Malfoy Manor, where Bellatrix proceeded to torture Hermione using the Cruciatus Curse.
Draco's refusal to reveal Harry's identity to Bellatrix was not because he liked him. It was because he believed that Harry was the only chance they had at defeating Voldemort. At first, Draco admired and revered Voldemort until he threatened his family's safety.
Quirrell didn't use the Killing Curse on Harry, because Voldemort said “use the boy” to get the Sorcerer's stone from the Mirror of Erised. If Quirrell had killed Harry right away, he would have lost the chance to get the stone.
The villain in the "Fantastic Beasts" movies is Gellert Grindelwald, who played a small but crucial role in the "Harry Potter" series. He was the wizarding world's biggest villain before Voldemort came along. In his youth, Grindelwald was friends with Albus Dumbledore, who was in love with him.
No. Snape did not know Quirrell was hosting Lord Voldemort during the events of Book 1. He tried to stop Quirrell from acquiring the Sorcerer's Stone on Dumbledore's orders.