Stunning Spell

The Stunning Spell is a charm that renders a victim unconscious and halts moving objects. It is commonly used in duels. The spell gains strength when many wizards cast it on the same target; for example, Minerva McGonagall had to be moved to St. Mungo's after being hit with the spell by multiple Ministry of Magic employees in 1996. The incantation for this spell is Stupefy.

Defence Against the Stunning Spell
The effects of a Stunning Spell may be counteracted by Rennervate, but will also wear off with time. It can also be deflected by a Shield Charm. Species known to be naturally resistant to the spell include dragons, trolls, giants and half-giants. Rubeus Hagrid was unaffected by this spell when, in 1996, several Ministry of Magic employees attempted to remove him from Hogwarts School of Witchcraft and Wizardry grounds.

It is also possible to bewitch objects to be resistant to the spell. Fred and George Weasley bewitched their fireworks to explode when hit by Stunning Spells.

Etymology
"Stupefy" comes from the Latin verb stupere, meaning "to be stunned."

Behind the scenes

 * In the books, it is described as a "jet of red light," but in the Harry Potter and the Order of the Phoenix (film), it's shown with a bluish-white that just knocks people off their feet.
 * In the Half-Blood Prince (video game) stupefy is shown as a jet of red light, as well as being green.

Appearances

 * 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 (video game)
 * Harry Potter and the Deathly Hallows