Joss Whedon has never hidden the fact that his vision for cheerleader-turned-vampire-killer Buffy Summers was heavily compromised on its way to becoming a flawed 1992 film.
In 1997, Whedon gave it another shot, producing a pilot for The WB that was set after the events of the film. Buffy moves to the small town of Sunnydale, where she starts at a new school, and meets her new "watcher," Rupert Giles. The town is built atop a "Hellmouth," and Buffy soon finds herself hunting again. Helping her are her new friends Xander and Willow, and eventually other additions like queen bee Cordelia, reluctant werewolf Oz, and morally conflicted vampire, Angel.
The series ran for seven seasons, and the story has since continued in officially licensed comic books. Angel eventually got his own spin-off, which lasted five seasons of its own.