Werewolf

The Werewolf is a human who upon the rising of the full moon turns into a fearsome wolf-like creature. 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 tend to look shabby and pale and are usually 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 venerable to attack.

Treatments
The only way to prevent this is to take the Wolfsbane Potion, which puts them in a wolf's body, but with a human mind, also there is some evidence that a werewolf who is taking a regular regimen of Wolfsbane Potion will not transform until the moonlight actually strikes him. The lycanthropy (werewolfism) spreads through bite, a human bit 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. The Homorphus Charm is also useful against werewolfs. Unfortunately there is nothing that will completely cure a werewolf.

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 with 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 instrumental in the passage of.

Due to the violent oppression and discrimination against werewolves by society, some persons who are werewolves have in turn come to hate their opressors and in turn, society in general. These werewolves have then organized themselves into their own society who then makes it their business to infect and destroy as many persons as possible.

Known Werewolves

 * Remus Lupin, bitten by Fenrir Greyback.
 * Fenrir Greyback, One of Voldemorts Death Eaters
 * Bill Weasley, attacked By Fenrir Greyback; Bill is not a full werewolf, although he does have some "wolfish features".
 * The Wagga Wagga Werewolf taught about by Gilderoy Lockhart during his time as Defence Against the Dark Arts Professor at Hogwarts, also likly 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.

Other

 * The term werewolf is used for both the wolf-like creature and the normal human who turns into the wolf at full moons.
 * 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 encountered Werewolves in the Black Forest, and at one point discussed in class how to treat werewolf bites. Also Snape assigned an essay during the 1993 school year when he once substituted for Lupin, although werewolves weren't due to be covered until the last chapter of the third-year DADA textbook.
 * It is said that there were werwolves in the Forbidden Forest.
 * Tom Riddle ounce accused Hagrid of raising "werewolf cubs" under his bed as a youngster though this was a lie as werewolves do not have cubs.