In the Harry Potter universe, it's possible to use magic unintentionally, the most famous example in the books is probably Harry blowing up his aunt.

Is there any reason to assume that wizards could (by accident or just because they're really mad) kill someone by this mechanism? What stopped Harry from actually blowing up his aunt? (Or just make an artery in her brain burst/ stop her heart etc)

I can't really believe that there is a system by the Ministry of Magic to prevent this kind of magic, because if there is, why doesn't it go as far as stopping Harry using magic in this way entirely?

I'm interested in a canonical answer (eg. information provided by JKR) since anything else is quite trivial.

EDIT I'm talking about a direct kill, not a death as a side-effect of an unintentional spell (eg. someone being killed by the snake Harry released)

EDIT 2 To clarify: By direcet kill I'm talking about a death resulting from a release of magical power caused by a thought like 'I want you to shut up'. Imagine that 'the magic' just takes it too far. For example: Harry inflated his aunt because he wanted her to stop talking, would it be possible that his aunt is actually killed by bursting, because that would definitely shut her up. In this regard, death is a side-effect, to the intention, but it is fulfilling the casters task whereas if the snake that Harry released were to kill someone I would not count it as a direct kill, because Harry did not release her with the intention to, for example, stop Dudley from talking trash about him.

  • 1
    I’m sure they could kill this way. There are instances of accidental deaths (stray curses, backfiring spells, etc.) in canon, although I can’t think of one that arose from unintentional magic.
    – alexwlchan
    Jul 7, 2014 at 13:34
  • What do you define as a direct kill?
    – CyanAngel
    Jul 7, 2014 at 15:59

5 Answers 5


The only known spell that can directly kill (i.e. not death as a consequence of the magical effects, burning, bleeding, summoning of deadly creature etc.) is the killing curse, Avada Kadavra.

It seems one cannot causally use this spell according to what Moody(Barty Jr.) says in GoF:

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 - Harry Potter and The Goblet of Fire.

On a similar vein (regarding the Cruciatus Curse):

You need to mean them, Potter! You need to really want to cause pain... to enjoy it... righteous anger won't hurt me for long...

—Bellatrix Lestrange - Harry Potter and The Order of The Phoenix.

These quotes imply that these curses require you to really mean them and require quite a lot of magical skill, and also some amount of experience.

With these quotes in mind it seems highly unlikely that someone could directly kill without intending to.

  • So in your view casting FiendFyre and killing people with it would not count as a direct kill? Jul 7, 2014 at 14:53
  • 1
    Quote from OP: "I'm talking about a direct kill, not a death as a side-effect". I believe the effect of FiendFyre is... fire, death is a side-effect. Just as you can survive the effects of a non-magical fire, you can survive the effects of a magical one.
    – CyanAngel
    Jul 7, 2014 at 14:57
  • That depends entirely on how you define death as a side-effect, if it means only something which has the soul purpose of killing then yes Avada Kedavra is the only curse(that we know of). In the same way as you have interpreted OP you could say bursting an Artery isn't a direct kill as they die from bleeding. "(Or just make an artery in her brain burst/ stop her heart etc)" - OP Jul 7, 2014 at 15:14
  • Hmm I see your point, I guess I'm not clear about the question, it seems I have focused on "the intent to kill through unintentional magic" rather than "the result of death through unintended but direct magic", but then we have to debate what is a side-effect and what is the effect. Inflating an aunt has the effect of causing her to float into the area, float too high and she could suffocate, is that an effect or a side effect?
    – CyanAngel
    Jul 7, 2014 at 15:18
  • It's in no way your fault and you are also not wrong, I think OP needs to redefine what he wants. There is accidental magic, intentional but uncontrollable magic and unintentional magic there are also varying ways to kill wizards that may or may not be a side effect depending on how you define it. Of course freeing a boa constrictor which then kills someone is a bit indirect but unintentionally killing someone by flinging them out a window, shocking them so their heart stops or dropping something on them. it needs defining by OP. Jul 7, 2014 at 15:24

There's definitely deadly results from even intentional magic. That seems to be an accepted part of life in Wizarding world.

Luna Lovegood's mother killed herself accidentally.

Vincent Crabbe killed himself with his own FiendFyre

Raczidian's own Patronus killed him

Fulbert the Fearful killed himself with a house collapse from defensive charm

Having said that, aside from people who are somehow damaged (like Ariana Dumbledore - who DID kill her mother Kendra accidentally) - adult wizards are generally capable of controlling their magic. So accidental unintentional magic would be confined to children, who generally aren't magically powerful enough to kill.

  • Are these direct deaths or deaths by side effect? Quote from OP: "I'm talking about a direct kill, not a death as a side-effect of an unintentional spell"
    – CyanAngel
    Jul 7, 2014 at 15:02
  • @CyanAngel Crabbe is arguably direct. Jul 7, 2014 at 15:15

Assuming you're talking about death caused by Accidental Wandless magic of the kind seen performed by Underage Wizards only in the books, we have at least one semi-concrete example of such a death -

Ariana Dumbledore accidentally killed her mother Kendra Dumbledore when she lost control of her magic and caused in an explosion (via Backfiring Jinx)

While this is death caused by explosion, the explosion is directly a result of accidental loss of control of magic, which seems to quite clearly be the most direct way of causing a death barring the Killing Curse itself, almost as directly as blowing someone up (in fact, it is blowing someone up!)

However, there is a possibility that the death was caused indirectly by the explosion (explosion causes a box to fall on Kendra's head!). Barring any additional information, however, the death is attributed to the explosion itself, so it seems that it is possible to kill someone with Accidental Wandless Magic.


All magic cast unintentionally seems to have a strong emotional trigger. There are several examples of this in the beginning of the first book but the simple "blowing up aunt" thing was triggered by rage.

Different individuals appear to have varying levels of magical power, regardless of their control. This increases as they age (at least into their teens).

The spells cast unintentionally do seem easily cabable of causing unintentional death whether direct or not.

The answer is, therefore, yes.

  • An untrained wizard (especially one who is not a child) seems capable of unintentionally casting a spell which could kill someone else in a despirate situation. This could especially occur in self defense. DVK as always is a genious and pointed out that Adriana Dumbledore killed her mother. She had little magically training and did so via an explosion in a fit. This was clearly an accident but her accidentablly casting magic due to her magical state. Clearly a more fatal "blowing up" due to rage.
  • A poorly trained or otherwise out of control wizard could cast a spell that kills himself or others. Crabbe is the best example. He cast a spell he was unable to handle. This is, however, unintentional. Another might be Harry almost killing Malfoy by casting a spell he does not know what it does.

The main reason I wrote an answer, however, is to address the "system by the Ministry of Magic to prevent this kind of magic". If a person is to own a gun, the best way to prevent unintentional killing via that gun is to ensure the person knows how to use it safely. If people are going to drive, the best way to prevent accidents is to teach them to drive safely. Wizards will use magic as they can. The public educations system known as Hogwarts exists, in part, to teach students how to control their magic to prevent such accidents. As "direct kills" are less common, the main goal seem to be to make sure they don't cause fatal or damaging accidents with more mundain spells. Industry would teach spells nessesary for work.

  • I am assuming any spell with the intent to kill is a "direct kill". Take or leave this explanation. I'd don't care if you cut off my head or just let me see a green light: dead is dead. Jul 7, 2014 at 17:50

It's certainly a possibility: Harry once released a snake in the zoo (by accident). That snake could have ended up killing other people (it didn't though).

Other possibilities are setting something on fire when angry, or transfiguring an item into something dangerous.

  • Hmm, these are examples of indirect killings, which is not what I meant. I was talking about a direct, unintentional use of magic powers. I'll edit the question to point this out.
    – cfrei89
    Jul 7, 2014 at 13:05

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