Howler

• Type: Magical Communication, Letter
• Owners: Various; notably sent by Molly Weasley, Augusta Longbottom, and Albus Dumbledore. Recipients include Ron Weasley, Neville Longbottom, Petunia Dursley, and Hermione Granger.
• Maker: Unknown; appears to be a common magical enchantment for letters.

A Howler is a magical letter that is delivered in a scarlet-red envelope. Upon arrival, it may be observed to be smoking faintly, hinting at the potent magic contained within. The primary purpose of a Howler is to convey a message in the sender's own voice, which has been magically amplified to a deafening volume. If a recipient hesitates or refuses to open a Howler, it will eventually explode and shout its message even more loudly than it would have otherwise. Once the message has been delivered in its entirety, the letter and envelope burst into flames and are reduced to ash, leaving no physical trace behind.

Howlers are enchanted to deliver a verbal message with extreme volume and force. They serve as a method of expressing immense anger, frustration, or displeasure, often with the intent of publicly shaming the recipient. The sender's voice is perfectly replicated, though magnified to an incredible degree, ensuring that everyone in the vicinity can hear the message. The enchantment includes a self-destruct mechanism, causing the Howler to burn up after its purpose is fulfilled. This prevents the message from being replayed or kept. The explosive consequence of ignoring a Howler serves as a powerful deterrent, forcing the recipient to face the sender's wrath immediately. While typically used for scolding, they can also be modified for malicious purposes, as seen when one sent to Hermione Granger contained harmful Bubotuber pus.

Howlers appear at several key moments throughout the series, often for dramatic or comedic effect.

• Harry Potter and the Chamber of Secrets: The first appearance of a Howler is when Molly Weasley sends one to her son, Ron Weasley, after he and Harry Potter illegally flew the enchanted Ford Anglia to Hogwarts. Delivered by the family owl Errol during breakfast in the Great Hall, it berates Ron in front of the entire student body, humiliating him completely.
• Harry Potter and the Prisoner of Azkaban: Neville Longbottom receives a Howler from his grandmother, Augusta Longbottom, after his carelessness with the dormitory password list allows Sirius Black to enter Gryffindor Tower. Like Ron, Neville is forced to open it in the Great Hall.
• Harry Potter and the Goblet of Fire: After Rita Skeeter publishes slanderous articles, Hermione Granger becomes the target of public animosity and receives multiple Howlers. One of these is weaponized, splashing her hands with undiluted Bubotuber pus upon being opened.
• Harry Potter and the Order of the Phoenix: In a more serious and critical use, Albus Dumbledore sends a Howler to Petunia Dursley at Number Four, Privet Drive. The Howler delivers a curt and powerful message—“Remember my last, Petunia.”—which successfully coerces her into allowing Harry to remain in her home, reminding her of the blood pact that protects him.

• In the film adaptations, the Howler is given a more elaborate visual design. The envelope magically folds itself into a paper mouth with teeth and a tongue, which then shouts the message before shredding itself. This origami-like appearance is a cinematic invention not described in the novels. (film)