The Stunning Spell is a spell that can render a person unconscious for a short period of time, or until the counter-spell - Rennervate - is used. The incantation is "Stupefy".
The spell's only effect is to knock a person unconscious, sometimes causing the person to be blasted off their feet in the process.
It won't work on creatures whose natural armour or blood seems to protect them, such as Giants or dragons. Combined Stunning spells can work where one fails, however. The effect of multiple spells seems to be much more powerful; when Minerva McGonagall was hit by four at once, the school matron Poppy Pomfrey was surprised that at her age this hadn't killed her, though it did lead to a short stay in St Mungo's Hospital for Magical Maladies and Injuries.
 Uses in the Books
 Third Book
 Fourth Book
After the Dark Mark had been cast in the aftermath of the Quidditch World Cup, Ministry of Magic officials quickly Apparated to the scene of the crime and, seeing three figures standing in the forest there, sent hundreds of Stunning spells their way. Unfortunately those three were not the real culprit, but Harry Potter, Hermione Granger and Ron Weasley. Harry managed to get the trio to duck in time, but, hidden in the bushes, Winky the house-elf was not so fortunate. She was found and accused of casting the spell. The real person to conjure it was Barty Crouch Jr., who had also been hit by the Stunning spells but was hidden under an Invisibility Cloak.
When four dragons were brought to Hogwarts for use in the Triwizard Tournament, it took combined Stunning Spells from several dragon-keepers for it to have an effect. Barty Crouch Jr. later used this spell on Viktor Krum to get him out of the way, leaving him free to murder his father.
In preparation for the Third Task of the Triwizard Tournament Harry Potter learnt how to use the spell. Hermione and Ron helped him to learn. This largely meant that they had to fall over again and again as Harry hit them with the spell. They had used cushions, but Ron seemed to be good at missing them. He suggested they use Mrs Norris instead.
During the task Crouch Stunned Fleur Delacour, who had time to scream. Harry tried to use the spell on a Blast-Ended Skrewt, but it rebounded off of its armour. He was more successful in Stunning Krum, who was under the Imperius Curse and trying to torture another Champion. Later that evening having faced Lord Voldemort and now escaping, Voldemort gave the instruction to Stun Harry, however he was able to dodge and hide behind headstones.
Safely back at Hogwarts Harry discovered that he was not so safe after all when the man he thought was Alastor Moody revealed himself to be Barty Crouch Jr. and a Death Eater. He was just about to kill Harry when Albus Dumbledore, Severus Snape and Minerva McGonagall used Stupefy, blasting down the door and knocking Crouch out in the process. In this weakened state the potion Veritaserum had an effect and through using it Dumbledore got a confession from him. It also turned out that the real Moody had been kept Stunned in his trunk throughout the year.
 Fifth Book
Dolores Umbridge uses the spell on one of Fred and George's fireworks. This turned out to be a mistake as, having anticipated this move, the twins had enchanted the fireworks to explode with force when hit.
When Umbridge attempts to sack Rubeus Hagrid, she brought with her five Ministry of Magic officials who attempted to Stun Hagrid as he made his escape. The spells had no effect thanks to his half-giant blood. Fang was hit, however. Minerva McGonagall saw what was happening and rushed out to protest and help him. But as she ran she was directly hit by four Stunning spells. Afterwards she had to be moved to St Mungo's Hospital for Magical Maladies and Injuries.
Umbridge later tries to Stun some Centaurs, but fails at a cost; she was carried away and not seen again for a while. Members of Dumbledore's Army who Harry had taught the spell to earlier in the year had better luck using it on the Inquisitorial Squad.
In the Department of Mysteries the spell was used many times when they were then ambushed by Death Eaters. Harry had the idea to distract them by destroying the surrounding prophecies after Bellatrix Lestrange tried to Stun Harry, but having been partially stopped by Lucius Malfoy hit and broke one. When Neville Longbottom tries to cast the spell with Hermione's wand and a broken nose he shouts "STUBEFY!" with no effect.
 Sixth Book
Hermone believes Severus Snape may have Stupefied Filius Flitwick after he delivered the news that Death Eaters were inside the castle. She and Luna Lovegood had been waiting outside Snape's office, and when he came out he told them that Flitwick had collapsed. Harry had tried to Stun Snape as he ran from the castle after killing Albus Dumbledore, but he missed.
 Final Book
The Stunning Spell is used multiple times when Death Eaters ambush members of the Order of the Phoenix and Dumbledore's Army who were trying to move Harry safely from Number 4, Privet Drive. The battle took place in mid-air. When the hood of one of his attackers slipped and was revealed to be Stan Shunpike under the Imperious Curse, Harry used the Disarming Spell rather than Stunning him. This move correctly identified Harry to the Death Eaters. Remus Lupin later challenged Harry on his choice, but Harry was adamant that at that height Stunning Stan would have been tantamount to killing him.
When trying to rescue Hermione from Malfoy Manor Harry gets hold of three wands and when using Stupefy hits werewolf Fenrir Greyback with the triple spell. Ron later uses the Stunning spell to protect Hermione when she disguised as Bellatrix Lestrange. A man had been trying to get her to tell him where his missing children were.
 Additional Canon
 The Films
In the Harry Potter and the Order of the Phoenix the spells seems to simply knock the victim to their feet, rather than knock them out. Also it is blue in colour.
 The Video Games
- ↑ 1.0 1.1 1.2 J. K. Rowling, GoF 9
- ↑ 2.0 2.1 J. K. Rowling, GoF 31
- ↑ 3.0 3.1 J. K. Rowling, GoF 34
- ↑ 4.0 4.1 4.2 4.3 J. K. Rowling, GoF 35
- ↑ 5.0 5.1 J. K. Rowling, OotP 32
- ↑ J. K. Rowling, PoA 20
- ↑ J. K. Rowling, GoF 19
- ↑ J. K. Rowling, GoF 28
- ↑ J. K. Rowling, GoF 29
- ↑ J. K. Rowling, OotP 28
- ↑ J. K. Rowling, OotP 31
- ↑ J. K. Rowling, OotP 21
- ↑ J. K. Rowling, OotP 33
- ↑ J. K. Rowling, OotP 35
- ↑ J. K. Rowling, HBP 29
- ↑ J. K. Rowling, HBP 28
- ↑ J. K. Rowling, DH 4
- ↑ J. K. Rowling, DH 5
- ↑ J. K. Rowling, DH 9
- ↑ J. K. Rowling, DH 23
- ↑ J. K. Rowling, DH 26
- ↑ J. K. Rowling, DH 30
- ↑ J. K. Rowling, DH 32