Ginger Snaps was released in 2000 and has gained significant reputation among horror fans as a very creative Werewolf movie. Also, as an obvious allegory for puberty and menstruation.
Ginger Snaps stars Katherine Isabelle and Emily Perkins as heavily emo sisters. Obsessed with death and suicide, the sisters are constantly antagonized by more "normal" teens at school. Ginger often defends her sister who is clearly far more awkward.
One night they sneak out of the house to steal another girl's dog as revenge for attacking them during gym class. While out, they're attacked by a massive wolf-like creature and Ginger is badly injured. Surprisingly she heals quickly and after a few comatose days is not in full health but is far more lively and social than she used to be. This begins to drive a wedge between her and her sister who feels the new "popular" Ginger is a betrayal. She begins to realize the changes aren't late-blooming puberty but is actually Ginger becoming a werewolf and enlists the help of the local *cough*herbalist to try to find a cure and save her sister.
All told, it's a good movie and definitely deserves its reputation as a very creative take on werewolves. The sisterhood and puberty themes are simultaneously beyond over-the-top and understated, with the superficial aspects taking front and center but the more subtle character beats just being. Also the creature effects are pretty damned good.
The movie has two sequels that came out in the same year as each other. The leads both return, which is nice. But given that Ginger Snaps 2 and Ginger Snaps Back came out within a few months of each other, I don't have much confidence in either of them being much good.
Next up: Skinwalkers