Killing Curse

"Avada Kedavra's a curse that needs a powerful bit of magic behind it - you could all get your wands out and point them at me and say the words, and I doubt I'd get so much as a nosebleed."

- Barty Crouch, Jr. as Alastor Moody

The Killing Curse is a spell that causes instantaneous death and is one of the three Unforgivable Curses. There is no known counter-curse or cure for it; however, one may dodge the green bolt, use a physical barrier to block it, or intercept the bolt with another spell. An explosion or green fire may result if the spell hits something other than a living target. Lord Voldemort was famous for using this curse regularly and indiscriminately. Its incantation is Avada Kedavra.

Appearance and Effect
The Killing Curse is described as a jet of blinding green light, which causes the victim instant death. There are no secondary effects; the victim simply "drops dead" for no biological reason. It is possible that the victim's internal organs cease function, or that once the spell hits a person's body, it simply kills every living cell in the victim's body. It could also cause sudden brain death, simply stopping the progress of every electrical synapse in the brain simultaneously by draining all potential energy there. A death caused by this curse may be physically painless; "echoes" of previous victims have asserted the death felt "quicker and easier than falling asleep". However, upon waking from his near-death experience, Harry Potter felt the curse's aftereffects and described it in a similar manner to that of an "iron-clad punch" to the chest.

Victims of the Killing Curse that have been examined with Muggle methods are known to show no visible signs of trauma. Though Muggle methods are unable to identify the means of death, Ministry of Magic specialists are familiar with the markings, or lack of them. The killing curse is known to leave no identifiable marks or any signs of the reason for death. Victims appear to "drop dead", or to appear "perfectly healthy apart from the fact they were all dead."

When this curse hits an inanimate target, its effect varies: it can produce small fires, small greenish explosions, or explosions of such intensity that can blow up an entire story of a cottage. However, certain objects, such as the centaur statue of the Fountain of Magical Brethren, managed to block the curse without any visible damage to itself.

Fatality
Only one person is known to have survived a direct application of the curse: Harry Potter, who was saved when his mother, Lily Evans, lovingly sacrificed herself by blocking the spell with her body. Over a decade later, Harry would survive the curse another three times: once during Priori Incantatem in his battle against Lord Voldemort in the graveyard in his fourth year. Again, in 1998 when the curse killed only the Horcrux inside him, and once more when the wand being used to curse him, the Elder Wand, refused to destroy him because Harry was its true master. This also makes Harry the only person to have survived the Killing Curse multiple times.

Lord Voldemort has survived the Killing Curse once when it backfired on him in 1981 (while attempting to kill Harry Potter). However, this was because he had Horcuxes at that time, and even so his body was still destroyed.

Phoenixes are also immune to the Killing Curse. In 1996, Fawkes swallowed one intended for Albus Dumbledore. He burst into flames, and was reborn from his ashes.

The Killing Curse can be survived if it is dodged or physically blocked by an object, such as the statues Dumbledore animated to protect Harry Potter during his duel with Voldemort after the Battle of the Department of Mysteries. Although considered unblockable by magic, as noted above there is a rare circumstance in which the Priori Incantatem effect can block it.

The Killing Curse is not the only spell that will cause death to a living creature. Other spells may cause injury or bleeding, such as Fiendfyre, Sectumsempra, possibly Antonion Dolohov's curse, if cast at a person, the Blasting Curse or Expulso, or an overuse of the Stunning Spell. References have been made to aurors using deadly force against opponents, but whether this means they were authorized to use the killing curse (i.e. a "licence to kill") is unclear. Despite the circumstances, it is unknown whether the curse was used by anyone but Voldemort and his Death Eaters during the Battle of Hogwarts.

Disputed Uses

 * Barty Crouch Jr admitted to the murder of his father, Barty Crouch Sr, but never identified his method of killing as the Killing Curse.
 * In 1996, Bellatrix Lestrange cursed Sirius Black with something that sent him through the Veiled Arch in the Department of Mysteries, but it has never been proven this was in fact the Killing Curse. In the film, she does use the Killing Curse.
 * Bellatrix Lestrange slew a fox with a nonverbal spell producing a "flash of green light" in 1996. However, it is not explicitly clear that she used the Killing Curse.
 * Similarly, Voldemort slew an unnamed Goblin after being brought the news of Harry and his friends breaching Gringotts and stealing his Horcrux. The Goblin, along with several others, was slain without incantation, but it is most likely that it was a Killing Curse.
 * Remus Lupin and Nymphadora Tonks were both killed during the Battle of Hogwarts, by Antonin Dolohov and Bellatrix Lestrange, respectively. Their bodies were described as peaceful-looking; the Killing Curse is known to not cause any external marks, though it is possible that they were killed with different spells.
 * Molly Weasley killed Bellatrix Lestrange with a spell that struck her in the heart, but it cannot be proven that she used the Killing Curse. Not only that, but Lestrange realized she was about to die; she did not die instantly, which is what the Curse causes.

Known Practitioners

 * Lord Voldemort
 * Barty Crouch Jr.
 * Peter Pettigrew
 * Draco Malfoy (possibly)
 * Thorfinn Rowle
 * Severus Snape
 * Vincent Crabbe
 * Bellatrix Lestrange
 * Lucius Malfoy (film only)

Etymology
Avada Kedavra is based on the Hebrew אבדא כדברא avada kedavra, meaning "I destroy as I speak". It is notably similar to "abracadabra", which is a famous word used as an incantation by magicians, and has, in actuality, the exact same root.

Behind the scenes

 * In Harry Potter and the Chamber of Secrets (film), Lucius Malfoy says "Avada" at Harry Potter after he unwittingly frees Dobby. Dobby knocks Lucius backwards with magic to protect Harry, and he doesn't finish the incantation. The part of the incantation shown, for plot reasons, was not represented in the subtitles. However, on the DVD if the audio is set to Spanish, Lucius clearly says "AVADA" to where it can be understood, in contrast the the English version, where he says it fast and it is almost hard to understand.
 * In Harry Potter and the Order of the Phoenix (film), Bellatrix Lestrange is shown using the Killing Curse to murder Sirius Black in a scene fundamentally different from that of the novel, in which Sirius was killed by being knocked into the veiled archway by an unknown curse cast by Bellatrix. The effect of the curse is also not shown to be instantaneous in the film.
 * A deleted scene from Order of the Phoenix, included on the DVD, could be interpreted as Dolores Umbridge talking herself into delivering the Killing Curse on Harry and Hermione. (She is interrupted by centaurs before she is able to utter any incantation.)

Appearances

 * Harry Potter and the Philosopher's Stone
 * Harry Potter and the Philosopher's Stone (film)
 * Harry Potter and the Chamber of Secrets (film)
 * Harry Potter and the Goblet of Fire
 * Harry Potter and the Goblet of Fire (film)
 * Harry Potter and the Goblet of Fire (video game)
 * Harry Potter and the Order of the Phoenix
 * Harry Potter and the Order of the Phoenix (film)
 * 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: Parts I and II

Notes and references
Avada Kedavra Avada Kedavra Авада Кедавра