Animagus

"Normally, I have a very sweet disposition as a dog. In fact, more than once, James suggested that I make the change permanent."

- Sirius Black, about his Animagus ability

An Animagus (pl. Animagi) is a witch or wizard who can morph him or herself into a specific animal at will. It is a learned, rather than hereditary, skill, unlike those of a Metamorphmagus. All known animagi in the series take the same form as their Patronus. It is unknown whether all do.

Aquiring the Skill
Only very powerful and skilled wizards are able to become Animagi. The process of becoming an Animagus is long and arduous, and has the potential to backfire and cause the transformation to go horribly wrong. Once the initial training is over, an Animagus can change at will at any time, with or without a wand.

Animagi can only take on the form of one specific animal. This animal form is not chosen by the wizard, but determined by their personality and inner traits. Thus, one's animagus form is a reflection of one's inner nature. It is unknown whether Animagi can take the form of a more "magical" creature

Each Animagus bears an identifying mark on their animal form that is caused by something on their human body. This may be a physical trait like dental structure, or an aquired trait such as glasses. For example, both Minerva McGonagall and Rita Skeeter have markings on their animagus forms caused by their spectacles. If an Animagus undergoes a major physical change, such as the loss of a limb, their animal form will also reflect that. Also, an animagus in animal form will retain the lifespan of an ordinary human being.

In addition, an Animagus will appear to lose their clothing upon morphing. The clothing will reappear upon reestablishing the human form. What physically happens to the clothing is unknown. A strong possibility, however, is that the clothing is enchanted beforehand, and will morph/disappear with the person as they do so. An example is when Peter Pettigrew morphs into a rat whilst Sirius Black and Severus Snape are occupied detaining the Werewolf-Remus Lupin. Another explanation is for the Animagus to concentrate upon their clothing, which may or may not have inverse effects upon morphing back to their human form.

Transfiguration vs. Animorphing
The difference between mere Transfiguration and the Animagus morphing ability is that an Animagus can change into an animal whenever they want, without a wand or an incantation. Being an Animagus is an ability, and Transfiguring requires a spell. An Animagus still thinks as a human does when they are in their animal form, seeing as Rita Skeeter was able to eavesdrop on humans' conversations when she was in the form of a beetle. However, an Animagus's feelings are not as complex when they are in their animal form.

An Animagus also has the ability to to communicate with normal animals. There seems to be a clear understanding of want and need in this communication ability, but the full extent and quality of it is unknown. Sirius Black's Animagus form, a black dog named Padfoot, was able to communicate on a rudimentary level with Crookshanks, Hermione Granger's part-Kneazle cat. The precise form of communication is yet unknown, though it is clearly not telepathy since Sirius did not know Crookshanks' name until Hermione told him.

There is a particular spell which creates a blue and white flash that will force an Animagus out of their animal form. Remus Lupin and Sirius Black once used it to force Peter Pettigrew out of his rat form. This spell could possibly be the Homorphus Charm Gilderoy Lockhart claims he used on the Wagga Wagga Werewolf to force him into his human form. However, given the source, the Homorphus Charm might not even exist, as Lockhart often told lies in order to boost his fame.

It is also important to note that a werewolf is fundamentally different from an Animagus. Lycanthropy is caused by a blood infection transmitted through the bite of a werewolf, whereas the Animagus skill is learned. The werewolves cannot keep their minds after a transformation (unless they take the Wolfsbane Potion), nor can they control when they wanted to transform, while Animagi can do both.

Wizarding Law
"Rita Skeeter isn’t going to be writing anything at all for a while. Not unless she wants me to spill the beans on her... I found out how she was listening in on private conversations when she wasn’t supposed to be coming into the grounds... Rita Skeeter is an unregistered Animagus. She can turn into a beetle... I've told her she’s to keep her quill to herself for a whole year. See if she can’t break the habit of writing horrible lies about people."

- Hermione Granger on her blackmail of Rita Skeeter

Every Animagus is required to register with the Ministry of Magic at the Improper Use of Magic Office. This registration includes revealing one's animal form and one's distinguishing markings. The Register is available to the public.

The penalty for failing to register as an Animagus is a sentence in Azkaban, though the length of time is unknown. Rita Skeeter gave up an entire year of writing articles, her main means of livelihood, so that Hermione Granger would not turn her in as unregistered, and consented to writing an article free of charge at Hermione's request.

Due to the complexity of the magic involved in becoming an Animagus, they have become very rare. There was a total of seven registered Animagi in the twentieth century. It is also partially because of this complexity, in addition to the danger involved, that Animagi are required to register themselves.

Known Animagi

 * Falco Aesalon — Falcon and the first recorded Animagus; the registration system was not in existance in his time.
 * Morgan le Fay — Bird; the registration system was not in existance in her time.
 * Cliodne - Sea Bird; the registration system was probably not in existence in her time
 * Minerva McGonagall — Cat; registered.
 * James Potter — Stag; unregistered.
 * Sirius Black — Dog; unregistered.
 * Peter Pettigrew — Rat; unregistered.
 * Rita Skeeter — Beetle; unregistered.
 * 6 unknown animagi — forms unknown; registered.
 * The fictional character Babbitty of the tale Babbitty Rabbitty and her Cackling Stump — Rabbit.

Etymology
Combination of the Latin words "animal" and "magus," meaning "animal wizard."

Behind the scenes

 * J.K. Rowling once joked that Godric Gryffindor was actually the Giant Squid in the Hogwarts lake. She has also stated that she would fancy an otter - her favourite animal - as her Animagus form.

Appearances

 * Harry Potter and the Philosopher's Stone
 * Harry Potter and the Philosopher's Stone (film)
 * Harry Potter and the Philosopher's Stone (video game)
 * Harry Potter and the Chamber of Secrets
 * Harry Potter and the Chamber of Secrets (film)
 * Harry Potter and the Chamber of Secrets (video game)
 * Harry Potter and the Prisoner of Azkaban
 * Harry Potter and the Prisoner of Azkaban (film)
 * Harry Potter and the Prisoner of Azkaban (video game)
 * 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 (film)
 * Harry Potter and the Deathly Hallows
 * Harry Potter and the Deathly Hallows (films)

Notes and references
Animagus