Willow Rosenberg is a fictional character in the popular television show, Buffy the Vampire Slayer played by Alyson Hannigan.
Warning: Wikipedia contains spoilers.
Willow was introduced in the first episode of the show as a fairly stereotyped brilliant high school nerd capable of performing any scientific or hacking trick needed to advance the plot. She had a hopeless crush on her lifelong friend Xander Harris, who ignored her to pursue his own equally hopeless crush on Buffy.
Subsequently Willow had a more satisfying relationship with Oz, a guitarist in the local band "Dingoes Ate My Baby". The relationship survived her discovery that Oz was a werewolf, and a more trying crisis when Oz and Cordelia Chase caught Willow and Xander kissing.
By this time Willow and the rest of the "Scooby Gang" had graduated from Sunnydale High School. Willow, who had begun performing simple spells after she met Jenny Calendar, was also by now a quite powerful witch.
Buffy and Willow moved across town to UC Sunnydale, where Willow attended some meetings of the campus Wicca group, a disappointing experience except for the presence of one student, Tara Maclay. After discovering their magic was more powerful if they performed in unison, they became friends, and later, lovers. Willow and Tara formed one of the very few lesbian couples portrayed in American television.
Willow's magical skills peaked in "Bargaining", the opening episode of season 6, where she joined with other members of the Scooby Gang to raise Buffy from the dead. Afterwards, she became obsessed with using magic constantly, which was portrayed with an occasional sledgehammer subtlety as being analogous to a drug addiction. Her magic addiction eventually led to Tara leaving her, and Buffy's sister Dawn being injured, the emotional consequences of which finally forced Willow to give up magic for good. Late in the sixth season, Willow's fury at Tara's tragic death unleashed the dark energies once again, and her vengeance reached a climax with the show's recurring theme of near-apocalypse. Willow would not make another attempt to abandon the use of all magic, but rather she was forced to deal with her magical nature, and come to grips with her place in the universe.
Willow appears to have survived an unenviable family life. Her supercilious and unaffectionate mother has appeared in only one episode. Her father, who has never been seen, is hinted to be not much of an improvement. No siblings have ever been mentioned.
The character of Willow is one of only three who remained a part of the series throughout it's run. The character grew from it's initial stereotype to be more complex as the series progressed.
