Willow plays an integral role within the inner circle of friends—called the Scooby Gang—who support Buffy Summers (Sarah Michelle Gellar), a teenager gifted with superhuman powers to defeat vampires, demons, and other evil in the fictional town of Sunnydale.

Her dependence on magic becomes so consuming that it develops into a dark force that takes her on a redemptive journey in a major story arc when she becomes the sixth season's main villain, threatening to destroy the world in a fit of grief and rage.

The Buffy series became extremely popular and earned a devoted fanbase; Willow's intelligence, shy nature, and vulnerability often resounded strongly with viewers in early seasons.

He began to develop for television the concept of a fashion-conscious girl named Buffy, who is imbued with superhuman abilities and attends a high school situated on a portal to hell.

[9][10] Willow is presented as a bookish nerd with considerable computer skills, dowdily dressed and easily intimidated by more popular girls in school.

They are mentored by the school librarian who is also Buffy's Watcher, Rupert Giles (Anthony Stewart Head), who often works closely with Willow in researching the various monsters the group encounters.

Joss Whedon found that Hannigan was especially gifted reacting with fear (calling her the "king of pain") and viewers responded strongly when she was placed in danger, needing to be rescued by Buffy.

Seth Green joined the cast during the second season as Oz, a high school senior who becomes a werewolf, and Willow's primary romantic interest.

"[14] At the end of the second season, Willow begins to study magic following the murder of the computer teacher and spell caster Jenny Calendar (Robia LaMorte).

Willow is able to perform a complicated spell to restore the soul of Angel (David Boreanaz), a vampire who is also Calendar's murderer and Buffy's boyfriend.

Willow becomes much more confident in college, finally finding a place that respects her intellect, while Buffy has difficulty in classes and Xander does not attend school.

Willow's relationship with her boyfriend, Oz, continues until a female werewolf appears on the scene, aggressively pursuing him, and he leaves town to learn how to control the wolf within.

Willow adapts to her newfound sexual identity, eventually falling in love with and choosing to be with Tara, even when Oz returns to Sunnydale after apparently getting his lycanthropic tendencies under control.

Throughout the series, magic is employed to represent different ideas -— relationships, sexuality, ostracism, power, and particularly for Willow, addiction -— that change between episodes and seasons.

[21] Through the gamut of changes Willow endures in the series, Buffy studies scholar Ian Shuttleworth states that Alyson Hannigan's performances are the reason for Willow's popularity: "Hannigan can play on audience heartstrings like a concert harpist... As an actress she is a perfect interpreter in particular of the bare emotional directness which is the specialty of [series writer Marti] Noxon on form.

Unfettered by the practical limitations of casting or a television special effects budget, Season Eight explores more fantastic storylines, characters, and abilities for Willow.

In Willow's dream, she moves from an intimate moment painting a love poem by Sappho on Tara's bare back,[note 1] to attending the first day of drama class to learn that she is to be in a play performed immediately for which she does not know the lines or understand.

As Willow gives a book report in front of her high school class, she discovers herself wearing the same mousy outfit she wore in the first episode of the show ("Welcome to the Hellmouth") as her friends and classmates shout derisively at her, and Oz and Tara whisper intimately to each other in the audience.

[40] Susan Driver writes that it is "crucial to recognize that never before in a teen series has raw fury been so vividly explored through a young queer girl responding to the sudden death of her lover".

Willow must control that part of her and is occasionally unable to do so, giving her a trait similar to Angel, a cursed vampire who fears losing his soul will turn him evil.

[51] Oz's trials in dealing with a power he cannot control is, according to authors J. Michael Richardson and J. Douglas Rabb, a model for Willow to reference when she encounters her own attraction to evil.

[57] In the fourth season episode "Hush", Willow meets Tara, and to avoid being killed by a group of ghouls, they join hands to move a large vending machine telekinetically to barricade a door.

[64] David Bianculli in the New York Daily News writes that Willow's progression is "unlike anything else I can recall on regular prime-time television: a character evolving naturally over four seasons of stories and arriving at a place of sexual rediscovery".

Susan Driver writes that younger viewers especially appreciate that Willow and Tara are able to be affectionate without becoming overly sexual, thus making them objects of fantasy for male enjoyment.

[79] Willow at times reminds the other characters of her religion, wondering what her father might think of the crucifixes she must apply to her bedroom wall to keep out vampires, and commenting that Santa Claus misses her house every Christmas because of the "big honkin' menorah".

Buffy essayist Matthew Pateman criticizes the show for presenting Willow's Jewish identity only when it opposes Christian declarations of holidays and other traditions.

Realistic depictions of lesbians are so rare that they become strong role models and enable "hope and imagination" for girls limited by the conditions of their immediate surroundings, who may know of no other gay people.

Manda Scott in The Herald states that Willow's lack of panic or self-doubt when she realizes she is in love with Tara makes her "the best role model a teen could ask for".

Jane magazine hailed Willow and Tara as a bold representation of gay relationship, remarking that "they hold hands, slow-dance and lay in bed at night.

Series writer and producer Marti Noxon—whose mother fell in love with another woman when Noxon was 13 years old—was unable to read some of the mail the writing team received because it was so upsetting.