Writer Joss Whedon says that "Rhonda the Immortal Waitress was really the first incarnation of [the Buffy concept], just the idea of some woman who seems to be completely insignificant who turns out to be extraordinary." This early, unproduced idea evolved into Buffy, which Whedon developed to invert the Hollywood formula of "the little blonde girl who goes into a dark alley and gets killed in every horror movie."Whedon wanted "to subvert that idea and create someone who was a hero." He explained: "The very first mission statement of the show was the joy of female power: having it, using it, sharing it."

The concept was first visited through Whedon's script for the 1992 movie Buffy the Vampire Slayer, which featured Kristy Swanson in the title role. The director, Fran Rubel Kuzui, saw it as a "pop culture comedy about what people think about vampires." Whedon disagreed: "I had written this scary film about an empowered woman, and they turned it into a broad comedy. It was crushing."The script was praised within the industry, but the movie was not.

Several years later, Gail Berman, a Sandollar Productions executive, approached Whedon to develop his Buffy concept into a television series. Whedon explained that "They said, 'Do you want to do a show?' And I thought, 'High school as a horror movie.' And so the metaphor became the central concept behind Buffy, and that's how I sold it."The supernatural elements in the series stood as metaphors for personal anxieties associated with adolescence and young adulthood. Whedon went on to write and partly fund a 25-minute unaired Buffy pilot that was shown to networks and eventually sold to the WB Network. The latter promoted the premiere with a series of History of the Slayer clips,and the first episode aired on March 10, 1997.