To make a wizard or witch invisible
An invisibility cloak is a magical garment which renders whatever it covers unseeable. They may be made from hair of Demiguise, a magical creature that possesses the power to become invisible. This property is used to make the wearer of the cloak invisible. However, as Xenophilius Lovegood tells Harry, Ron, and Hermione, such a cloak will gradually lose its effectiveness as the hair becomes more and more opaque. The cloak can also be formed from an ordinary travelling cloak, enchanted with an exceptionally strong disillusionment charm or a bedazzling hex. The cloak is also mentioned by being one of the entities in the Deathly Hallows. In the story the third brother asked for a way to hide from Death so Death himself gave the brother the cloak of invisibility.
There are ways of making one's self invisible by using magic other than invisibility cloaks. An example is the Disillusionment Charm. Dumbledore once remarked to Harry that he didn't need a cloak to become invisible.
People who have used invisibility cloaks
- Ignotus Peverell used the Cloak of Invisibility to hide from Death.
- Ignotus Peverell's son was given the Cloak of Invisibility by Ignotus Peverell.
- James Potter owned an invisibility cloak (actually one of the fabled Deathly Hallows) that he and his friends often used during their days at Hogwarts to assist them in their mischief. Albus Dumbledore had James's cloak at the time of the latter's death, having wished to inspect it further. He kept the cloak in his possession until Harry began school at Hogwarts in 1991.
- Harry Potter used his father's cloak many times throughout his years at Hogwarts. He received it from Albus Dumbledore anonymously in 1991 as a Christmas present.
- Hermione Granger, Ron Weasley, Severus Snape and Luna Lovegood also used Harry Potter's invisibility cloak.
- Barty Crouch, Jr., having escaped from Azkaban prison, was kept hidden by his father under an invisibility cloak at their home. He also watched the Quidditch World Cup in 1994 while under an invisibility cloak.
- Mundungus Fletcher was loaned an invisibility cloak by Mad-Eye Moody for Order of the Phoenix business. It is likely that Mundungus used the cloak for other, less reputable purposes.
- Mad-Eye Moody lent Sturgis Podmore his best invisibility cloak in 1995 to assist in guarding the Prophecy in the Department of Mysteries. He mentioned that Podmore had not had the manners to return it in a timely fashion and forced Moody to use his second best cloak. This was because Podmore had been placed under the Imperius Curse by Death Eaters.
The invisibility cloak of legend
The Tale of the Three Brothers, a wizarding legend, speaks of a Cloak of Invisibility which (shortly after Christmas 1997) Xenophilius characterises as one which "endures eternally, giving constant and impenetrable concealment, no matter what spells are cast at it." This cloak of legend is actually the one that James Potter had owned, and was later given to Harry Potter, because the Potters are in fact descendants of the youngest Peverell Brother, Ignotus Peverell.
Ron Weasley was the first to speculate that Harry's cloak is indeed among the famed Deathly Hallows, since it was at least two generations old (James Potter and then Harry), and most invisibility cloaks wear out after that time, or at least lose some effectiveness, yet Harry's was as good as new, which raised suspicion. Invisibility cloaks often become opaque with age, rip, have the charms placed upon them wear off, or have them countered with charms of revealment.
- Harry Potter and the Philosopher's Stone (First appearance)
- Harry Potter and the Philosopher's Stone (film)
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- Harry Potter and the Chamber of Secrets
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- Harry Potter and the Prisoner of Azkaban
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- Harry Potter and the Goblet of Fire
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- Harry Potter and the Order of the Phoenix
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- 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 (video game)
- Harry Potter and the Deathly Hallows: Part 2 
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