Werewolf

Werewolves are a race of supernatural partially human creatures, able to morph into a combination of human and wolf during the period of a full moon, that have encountered by hunters such as Sam and Dean Winchester. It has been stated that werewolves and skinwalkers are cousins. There is no known cure for lycanthropy.

They have been seen only in "Heart" and "Bitten" and they have been mentioned in eight other episodes.

Characteristics
Werewolves are humanoid carnivores, the ultimate combination of wolves and humans. They feed on prey found nearby, which, due to the increase of urban areas, are mostly humans. In the series, w hen they devour the flesh of victim they leave a recognizable trace on the prey: they always eat the heart, they do sometimes eat more of the body, but never leave the heart. T he transformation only occurs after oral contact of the beast with the victim, the way werewolves continue the spread of lycanthropy.

It is shown that they can only turn into a werewolf when they are asleep - as Samand Dean checked if they succeeded in stopping Madison from turning into a werewolf again by remaining in her apartment during a night under a full moon, and no werewolf transformation was seen, yet the next night she did change and tried to hunt again.

In their werewolf form, their bodies change rapidly, changing into a fitting definition of predators. Their nails increase to sharp, long claws, fangs increase in size and eyes resemble those of a wolf rather than of a human. In the series, unlike folklore and movies, they do not grow fur.

In the series, the people affected by the disease have a short-term memory loss, often living them in confusion of wounds which might have been caused during the night. In the series, Dean manages to cut Madison with a silver knife, making her wonder how was the wound created.

Despite being the person having no control, certain fragments of their personality and fears can still be in the wolf's mind, especially strong ones, as such suppresed fears or aggression can drive them to kill in there Beast form, aswell as hunger.

In pureblood werewolves, ones that are closer to the Alpha, the wolves have more control over themselves and are less feral. Their human side retains a lot of control and they remember what happened afterwards and can transform anytime they want. Purebloods also can feed on just animal hearts, but if they get a taste of human hearts, its harder to control themselves and they will be drawn to eating human hearts with a much harder time controling themselves.

Known Powers

 * Shapeshifting - Werewolves transform into a wolf-like creature only under a full moon. However, in season 6, All Dogs Go to Heaven, Sam tells Dean that werewolves no longer change under a full moon, but under half moons. The demon Crowley agreed with Sam by saying "werewolves changing under a full moon, so... 09."
 * Infectious bite - A werewolf can turn anther person into a werewolf by oral contact while in beast form.
 * Powerful Claws and Fangs - Werewolves have powerful claws and are able to cut solid walls. Thier fangs can tear off and eat human fleah and can rip out a human heart right out of thier chest cavity.
 * Enhanced Strength - A werewolf's strength is greater then human's. They can ezay overpower humans and can rip flesh and bones with amazing force.
 * Enhanced Agility - Their agility is greater than humans, often allowing them to perform incredible jumps and sprints easily.
 * Enhanced Speed - A werewolf can move faster than both man and wolves.
 * Superhuman Stamina - Werewolves don't tire easily.
 * Night Vision - All werewolves are able to see better than humans in darkness, similar to actual wolfs
 * Invurability - Only Silver can harm or kill werewolves.

Weaknesses

 * Silver - A werewolf's only known weakness is their vulnerability to silver, as they can be killed with a silver knife or bullet. Contact of werewolf skin and silver will hurt them.
 * Vamp-Tonite - Edgar states the Leviathan additive will kill wolves as well as vampires. (There Will Be Blood)
 * Being torn to shreds - Kate is able to kill Brian Wilcox by ripping him to shreds.

Known Werewolves
There have been six werewolves that have been on the series:
 * Madison
 * Glen
 * College Proffesor
 * Mike
 * Brian Wilcox
 * Kate

Trivia

 * Have been mentioned more often than any other monster, but have only appeared once.
 * Due to there great physical prowess, Werewolves seem to be highly respected monsters in hunter comunities, as stating they've hunted them is seem as sign of achievement.