Hallowe'en in the Wizarding World

• Type: Annual Magical Event
• Location: 31 October; observed throughout the Wizarding World
• Owner/Residents: Witches and Wizards; Hogwarts School of Witchcraft and Wizardry (notable celebrations)
• Key Features: Elaborate feasts, magical decorations, a night of immense historical and personal significance for Harry Potter

Hallowe'en, celebrated on the 31st of October, is a major event in the wizarding calendar, observed with far more enthusiasm than in the Muggle world. At Hogwarts School of Witchcraft and Wizardry, the occasion is marked by a grand feast in the Great Hall. The hall is lavishly decorated with thousands of live bats fluttering from the enchanted ceiling, and hundreds of carved pumpkins, some large enough for three men to sit in, which are said to be grown by Rubeus Hagrid. The feast includes a variety of Hallowe'en-themed magical foods and sweets. Beyond the Hogwarts feast, Hallowe'en holds a deeper cultural significance. It is, for instance, the “deathday” of many ghosts, including Nearly Headless Nick, who in 1992 celebrated the 500th anniversary of his botched execution with a Deathday Party in the Hogwarts dungeons. The date is intrinsically linked to powerful magic and fateful events, repeatedly serving as a turning point in the wizarding world's recent history, particularly concerning Harry Potter and the rise and fall of Lord Voldemort.

The date of 31 October is a recurring and pivotal fixture in the narrative, with a major plot development occurring on Hallowe'en in each of the first four novels.

• 31 October 1981: Lord Voldemort travels to Godric's Hollow and murders James and Lily Potter. When he turns his wand on the infant Harry Potter, the Killing Curse rebounds, destroying Voldemort's body and ending the First Wizarding War. Harry is left with only a lightning-bolt scar, becoming known as “The Boy Who Lived”.
• 31 October 1991: During the Hallowe'en feast, Professor Quirrell, secretly acting on Voldemort's orders, lets a fully grown Mountain Troll into the Hogwarts dungeons as a diversion to steal the Philosopher's Stone. Harry and Ron Weasley defy school rules to warn Hermione Granger and end up saving her from the troll in a girls' bathroom, a terrifying ordeal that forges their enduring friendship.
• 31 October 1992: While attending the 500th Deathday Party of Nearly Headless Nick, Harry hears the disembodied voice of the Basilisk for the first time. Later that evening, he, Ron, and Hermione discover the petrified body of Argus Filch's cat, Mrs Norris, hanging by her tail, and a message written in blood on the wall: “THE CHAMBER OF SECRETS HAS BEEN OPENED. ENEMIES OF THE HEIR, BEWARE.”
• 31 October 1993: The mass murderer Sirius Black successfully infiltrates Hogwarts Castle. He slashes the portrait of the Fat Lady with a knife when she refuses him entry to Gryffindor Tower. The attack causes panic and forces the students to sleep in the Great Hall under the teachers' protection.
• 31 October 1994: The Goblet of Fire is scheduled to choose the champions for the revived Triwizard Tournament. It selects Fleur Delacour from Beauxbatons Academy of Magic, Viktor Krum from Durmstrang Institute, and Cedric Diggory from Hogwarts. However, the Goblet then mysteriously produces a fourth name: Harry Potter, binding him in a magical contract to compete in the dangerous tournament.

J.K. Rowling's use of Hallowe'en draws on its real-world Celtic origins as Samhain, a festival marking the end of the harvest season and the beginning of winter. In folklore, this is a time when the veil between the world of the living and the world of the dead is at its thinnest (Pottermore). This theme resonates strongly within the series, especially given that the foundational event of the story—the murder of Lily and James Potter and the “death” of Lord Voldemort—occurs on this night. After the fourth book, significant events cease to fall on Hallowe'en, a deliberate narrative choice by the author to avoid the plot device becoming too predictable.