Dedicated to the species known as the werewolf in Monster Mash.
Werewolves generally can't remember anything from the night before they were bitten and turned, and this is a drawback that affects most. Those who can remember are considered either very lucky or very unfortunate. Lucky because they know who they are, and unlucky because... would you want to go home to your family like that?
Every werewolf pack has an Alpha, a leader, and while packs are scattered throughout the world with no communication, when they pass each other it is generally with amiable interests. The Alpha of the pack is determined by who is the most assertive, strong and best at hunting. More often than not, the Alpha will also be the one to have turned his or her pack mates, building a pack the same way vampires build covens.
Werewolves and vampires have been enemies since the dawn of time, something which is written in to their psyches as a species prompts even the gentlest of werewolves to pounce, snarling, at a vampire.
They can change partially into their wolf form at any time, but it has to be night time before they can turn fully into wolves. They can do this at any time apart from when there is no moon, when they're stuck at half-transformed. When there is a full moon, they are forced into becoming wolves whether they want to or not, and lose all sense of self in the process. Once the moon sets, though, they regain their conscious thoughts and can turn themselves back.
Werewolves on average are between twice or three times the size of a normal wolf. This, as well as their distinct patternings, is often enough to tell them apart from a distance.
It should be noted that werewolves are not immortal or even particularly long-lived. Their lifespan is that of a healthy human's, 90 years at best to 60 at least.