Godric Gryffindor's Sword
The Sword of Godric Gryffindor is Goblin-made, and as such takes in the strengths of whatever it touches. Because of this, it can destroy horcruxes after taking in basilisk venom when Harry stabbed the Basilisk in The Chamber of Secrets.
 Chamber of Secrets
The Sword appeared in the Chamber of Secrets during Harry's battle with the Basilisk after Fawkes flew in and dropped the Sorting Hat sent by Albus Dumbledore. During the battle, Harry cast the sword into the roof of the Basilisk's mouth, piercing through the flesh and impailing the creatures brain, killing it almost instantly. However, Harry's arm had caught on the fang of the Basilisk during this attack and had been injected with the poison of the Basilisk. Fawkes was able to heal the wounds Harry had sustained with his tears. Harry then used the fang to destroy his first Horcrux - Tom Riddle's Diary
 Deathly Hallows
The sword reappeared again in the Deathly Hallows, coming to the aid of Harry Potter. It was at the bottom of a small, frozen lake, found by Harry after following a Doe shaped Patronus charm, later revealed to have been the creation of Severus Snape. Ron Weasley was also lead by the same Patronus, reuniting Harry and Ron after Ron had left Harry and Hermione several weeks earlier, having been tainted by the anger of the Horcrux that he wore around his neck. Ron saved Harry from drowning in the small lake after the same Horcrux refused to go near the Sword of Gryffindor, almost strangling Harry in the process. Once the sword was obtained, Ron used to to destroy their third Horcrux - Salazar Slytherin's Locket.
Once laced with the poison of the Basilisk fang Harry killed during the events of Harry Potter and the Chamber of Secrets, the sword was also used to destroy the other Horcrux's created by Voldemort, bar Harry himself. These included; Helga Hufflepuff's Cup, locked in Bellatrix Lestrange's vault at Gringotts, and Nagini. The latter was killed by Neville Longbottom who had gained ownership of the sword, allowing Harry Potter to deal with killing blow that defeated Lord Voldemort.