Werewolf

The Werewolf is a human who, upon the rising of the full moon, turns into a fearsome near wolf (or wolf-man in the movie versions). Werewolves can be distinguished from regular wolves by several small distinguishing characteristics, such as the pupils of the eyes, snout shape, and tufted tail. When in human form, werewolves look and act like any normal human being, although usually appear to be ill around nights were there is a full moon. Transforming into a werewolf was known to be a difficult and painful process, and when isolated from humans or the company of other animals, the werewolf would attack itself with its own teeth and claws out of frustration. When in wolf form, the werewolf does not keep the mind of the human form, and it cannot resist attacking humans; even the werewolf's best friends are vulnerable to attack.

Treatments
Unfortunately there is nothing that will completely cure a werewolf. The only way to keep a transformed werewolf rational is to take the Wolfsbane Potion, which allows the werewolf to retain his or her human mind. Also, frequent users of this potion seem to refrain from transforming until they are in direct contact with the moonlight. As lycanthropy (werewolfism) is spread through some oral means (probably saliva, though Rowling doesn't say), a human bitten by a werewolf in wolf form will become a werewolf. However, if a human is bitten by a werewolf in human form, they will usually only adopt lupine (wolf-like) tendencies. According to Gilderoy Lockhart, the Homorphus Charm can force a werewolf back into human shape. But, since Lockhart implies that the charm cures werewolves, his information is highly suspect — as is the very existance of a Homorphus Charm in the first place.

Public view
Werewolves are generally frowned upon and feared by society. It is not uncommon for persons known to be werewolves to be shunned by society and discriminated within the Wizarding World. While the reason for discrimination is unfounded, since the invention of the Wolfsbane Potion, fear and hatred of werewolves stem from the incurable nature of bites and the level of violence from attacks. It is very difficult for a werewolf to get a job in the wizarding community, especially after the passing of restrictive anti-werewolf legislation, of which Dolores Umbridge was an instrumental supporter.

Due to the violent oppression and discrimination against werewolves by society, some persons who are werewolves have in turn come to hate their oppressors and, in turn, society in general. These werewolves have organized themselves into their own society. Under Fenrir Greyback's leadership, this society works to infect as many people as possible, especially children (as a terrorist-style tactic). The werewolves under the command of Fenrir Greyback served Voldemort in the Second War, though Remus Lupin spied on them for the Order of the Phoenix.

Known Werewolves

 * Remus Lupin, bitten by Fenrir Greyback.
 * Fenrir Greyback, honorary Death Eater.
 * Bill Weasley, attacked by Fenrir Greyback while he was in human form; Bill is not actually a werewolf, although he does have some "wolfish features".
 * The Wagga Wagga Werewolf, discussed by Gilderoy Lockhart during his time as Defence Against the Dark Arts Professor at Hogwarts, also discussed in his book Wandering with Werewolves.
 * A werewolf on Arthur Weasley's ward during his stay at St Mungo's Hospital for Magical Maladies and Injuries, this new werewolf was befriended by Lupin.
 * Teddy Lupin, a half-werewolf. The effects of being a half-breed are unknown, but it is likely that half-breeds only develop wolfish features, like Bill, based on Deathly Hallows (both the chapter soon after his birth and the epilogue). Since Rowling has been vague as to whether lycanthropy is genetic or an illness (she switches back and forth in the books), the effect on Teddy is unclear.

Other

 * The term werewolf is used for both the wolf shape and the human form.
 * The Ministry regulates werewolves. Already in 1637 there was a Werewolf Code of Conduct, and according to Newt Scamander, werewolves have been shunted between the Beast and Being Divisions of the Department for the Regulation and Control of Magical Creatures for years. At one point, the Werewolf Registry and Werewolf Capture Unit were both in the Beast Division, while at the same time the office for Werewolf Support Services was in the Being Division.
 * Professor Quirrell had the first year DADA class copy notes about how to treat werewolf bites. Also Snape assigned an essay during the 1993-1994 school year when he substituted for Lupin, although werewolves weren't due to be covered until the last chapter of the third-year DADA textbook.
 * According to Draco Malfoy and Argus Filch, there were werewolves in the Forbidden Forest. However the truth of this matter is unclear, as it may have been a rumor.
 * Tom Riddle once accused Hagrid of raising "werewolf cubs" under his bed as a youngster, though this was probably a lie. It is unknown whether werewolves have cubs or not — Lupin was worried that it might be possible to pass his affliction on his son, but Scamander suggests otherwise. Since Riddle was trying to frame Hagrid, the veracity of his statement is questionable.

Appearances

 * Harry Potter and the Philosopher's Stone
 * Harry Potter and the Philosopher's Stone (film)
 * Harry Potter and the Chamber of Secrets
 * Harry Potter and the Chamber of Secrets (film)
 * 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 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 Deathly Hallows