Derek Hale

Derek Hale is a dark and mysterious character who's past, secrets and motives remain unknown. He is currently Scott's mentor, teaching him aspects of being a Werewolf. He is physically very strong and attractive and can be sadistic and cruel, but he is loyal to his kind.

During a full moon (while in werewolf form) he bites Scott McCall, thereby starting the transition to a werewolf.

Derek's whole family was wiped out in a fire, though his sister was found dead and ripped in half not too long ago. It is unknown wether or not he actually did kill her, but it is interesting to note that they both seem to be different types of werewolves. According to the bonus clips from MTV, Derek is a born werewolf as well as an alpha. He is able to turn himself completely into the more historically known 'bestial form,' as well as a partial man/wolf.

It is possible that born werewolves such as Derek and his sister are the only one's to be able to transform completley into wolves and a wolf/man because they are pure blood (born as wolves), as where as turned/bitten werewolves might lack he abilty because they are not pure blooded (born) werewolves.