Vincent Crabbe, a student at Hogwarts School of Witchcraft and Wizardry, is responsible for the destruction of the Ravenclaw Horcrux. In the Harry Potter and the Deathly Hallows book, Crabbe unwittingly destroys Rowena Ravenclaw’s diadem in the Room of Requirement via Fiendfyre.
The Ravenclaw Horcrux was one of the seven Horcruxes created by Lord Voldemort to contain pieces of his soul and ensure his immortality. It was a diadem belonging to Rowena Ravenclaw, the founder of Ravenclaw House. The diadem was hidden in the Room of Requirement, a secret room at Hogwarts.
In the Deathly Hallows, Crabbe is sent by Voldemort to find and retrieve the diadem. He casts a powerful Fiendfyre spell in the Room of Requirement, unaware that the diadem is hidden in the room. The Fiendfyre quickly spreads and engulfs the room, destroying the diadem and killing Crabbe in the process.
Hermione Granger and Ron Weasley had previously destroyed the Hufflepuff’s cup Horcrux inside the Chamber of Secrets—Hermione giving it the fatal blow with a basilisk fang. With the destruction of the Ravenclaw Horcrux, all of Voldemort’s Horcruxes were destroyed, making him vulnerable to attack.
Vincent Crabbe’s death was a tragic one, but his unwitting destruction of the Ravenclaw Horcrux ultimately proved to be a key moment in the defeat of Lord Voldemort. Without the destruction of the Horcruxes, Voldemort would have remained invincible. Crabbe’s death was a small price to pay for the ultimate victory of good over evil.