Willow Rosenberg
Willow Rosenberg was born to Ira and Sheila Rosenberg; she is the only Jewish member of the Scooby Gang. She doesn't appear to have the most superb family life; her parents are out of touch with Willow's life, and her mother once tried to burn her at the stake.
Willow has been friends with Xander since childhood (when they were five, they "dated" briefly until Xander stole her Barbie doll), and she quickly became best friends with Buffy when she came to town.
Willow is extremely intelligent, a whiz on computers, and an excellent student who is known for her tutoring abilities. She has helped Buffy and Giles numerous times by hacking into various records and databases, and she even taught Jenny Calendar's computer class after Jenny was killed by Angelus.
Willow has long had "more than friends" feelings toward Xander, and after years of ignoring her, Xander finally seemed to return those feelings — while the two were both dating other people. When Oz and Cordelia found out about their indiscretion, they ended it, and Willow and Oz were able to save their relationship. Willow will probably always have a soft spot for Xander, as demonstrated by her crying jag when she found out that Xander had slept with Faith. Nonetheless, she and Oz seem very happy together, and Willow has since lost her own virginity to Oz.
Willow has been dabbling in the occult, and is interested in becoming a "bad ass Wicca" (she probably won't be turning any frogs into princes, though, since she has frog fear). She has successfully performed a few spells, but has been unable to turn Amy (who turned herself into a rat) back into a human. Willow had a hard time when Oz left, but is doing well lately, and enjoying her new friendship with fellow Wiccan Tara. She has recently found love with Tara, and they are now in a relationship.