Disarming Charm

The Disarming Charm is a defensive spell that aims to disarm an opponent, causing whatever is in the persons hand at the time, usually a wand, to fly out of his or her hand. It has been known to knock an opponent backwards in some cases. The charm's incantation is Expelliarmus.

Appearance and effect
The Disarming Charm can vary in colour and in its precise effects. Sometimes, it manifests as a "jet of red light", and knocks the victim backwards as well as disarms him or her. This is what happened to Viktor Krum in 1995. On other occasions, the charm does not have a colour, and instead simply makes a wand fly from the victim's hand. When Severus Snape cast the spell on Gilderoy Lockhart, it was shown as a scarlet ring surrounding the wand, with a streak of scarlet light heading towards Lockhart.

When Cho spoke the incantation incorrectly, Expellimellius, it set her friend Marietta Edgecombe's sleeve on fire. Sometimes when the spell is done weakly but not incorrectly it can make someones hair just stand on end or blow them back a few paces.

Harry Potter's signature spell
Many people considered the Disarming Charm to be the signature spell of Harry Potter. Despite being taught it by the teacher he despised the most (Severus Snape, until the events of 1997), Harry found it quite useful and utilised it often in direct confrontation with another wizard. He became highly proficient with it in 1994 when practising for the Triwizard Tournament. At the end of the tournament, after he and Cedric Diggory were transported to the graveyard in Little Hangleton and Cedric was murdered, Harry faced the newly-restored Lord Voldemort in a duel. Voldemort used the Killing Curse and Harry used the Disarming Charm. Due to the natural brotherhood of Harry's wand and Voldemort's wand, both containing cores from the same source (that source being Fawkes, the pet Phoenix of Albus Dumbledore), both duellers' spells proved ineffective, creating the rare Priori Incantatem effect which greatly contributed to Harry's subsequent escape.

Many Death Eaters witnessed this, and took to believing that it was Harry's signature move. In the Battle over Little Whinging, they identified him as the real Harry Potter out of the "seven Potters" once he used the Disarming Charm against the Imperiused Stan Shunpike. Remus Lupin later chided Harry for using Expelliarmus in battle conditions, but Harry continued to value it; his argument being that hitting Stan with a stunning spell, as Lupin had suggested, could have ultimately killed him after falling from such a height. In his final duel with Voldemort during the Battle of Hogwarts, Harry again used a Disarming Charm against Voldemort's Killing Curse, repeating the event of 1994 with the exception of a Priori Incantatem effect taking place. This time, it was Harry's rightful ownership of the Elder Wand, being wrongly used by Voldemort, that led to Harry's victory. A property of the Elder Wand, it seems, is that it will refuse to physically harm its true master. Should it be forced to do so, as Voldemort did, the spell cast from the wand will have a mild to no effect on the target. Hence, upon meeting Harry's Disarming Charm in mid-air, the Killing Curse intended for the latter, rebounded on Voldemort, killing him immediately.

Known practitioners

 * Albus Dumbledore
 * Cedric Diggory
 * Colin Creevey
 * Dennis Creevey
 * Draco Malfoy
 * Dumbledore's Army
 * Ernie Macmillan
 * Fred Weasley
 * George Weasley
 * Ginny Weasley
 * Harry Potter
 * Hermione Granger
 * James Potter
 * Lord Voldemort
 * Luna Lovegood
 * Neville Longbottom
 * Remus Lupin
 * Ron Weasley
 * Severus Snape
 * Sirius Black
 * Zacharias Smith

Behind the scenes

 * In the Doctor Who episode 'The Shakespeare Code', the spell is mentioned in connection to the Harry Potter books, with the Doctor stating "good ol' JK" after Shakespeare uses the word Expelliarmus to conclude a 'magical' formula to banish the episode's villans, the Carrionites, from Earth.
 * Expelliarmus has probably the most inconsistent effects of any spell of the series. In the Chamber of Secrets and Prisoner of Azkaban video games, Expelliarmus conjures a shield, identical in its effects to the books' Protego (used to repel the opponent's attacks), and does not physically "disarm" the opponent at all, though it is still called the "Disarming Charm". In Order of the Phoenix, Expelliarmus was used to finish (disarm) opponents. It doesn't appear in Philosopher's Stone, and in Goblet of Fire it's only seen in a cutscene and as part of Priori Incantatem. In the Half-Blood Prince video game, it appears as a projectile cloud of blue and violet energy which blasts the victim off their feet, but does not send their wand flying.
 * In the film series, Expelliarmus is used many times. Snape uses it first, at the Duelling Club, blasting Gilderoy Lockhart through the air without actually disarming him. In Prisoner of Azkaban, it regains its official effects, used many times to simply knock the wand from the target's hand without physically assaulting them, except for when used by Harry against Snape, though this could be attributed to Harry using Hermione's wand at the time, a feat which can have unpredictable effects for any wizard.
 * Upon meeting with Severus Snape, Albus Dumbledore used a possible variation of the Disarming Charm, which seemed to utilise the effects with lightning speed.

Appearances

 * Harry Potter and the Chamber of Secrets
 * Harry Potter and the Chamber of Secrets (film)
 * Harry Potter and the Chamber of Secrets (video game)
 * Harry Potter and the Prisoner of Azkaban
 * Harry Potter and the Prisoner of Azkaban (film)
 * Harry Potter and the Goblet of Fire
 * Harry Potter and the Goblet of Fire (film)
 * Harry Potter and the Order of the Phoenix
 * Harry Potter and the Order of the Phoenix (film)
 * Harry Potter and the Order of the Phoenix (video game)
 * Harry Potter and the Half-Blood Prince
 * Harry Potter and the Half-Blood Prince (film)
 * Harry Potter and the Half-Blood Prince (video game)
 * Harry Potter and the Deathly Hallows
 * Harry Potter and the Deathly Hallows: Part 1
 * Harry Potter and the Deathly Hallows: Part 1 (video game)
 * Harry Potter and the Deathly Hallows: Part 2
 * Lego Harry Potter Years 1-4

Notes and references
Expelliarmus Sortilège de Désarmement Expelliarmus Aseistariisuntaloitsu