Poison Ivy (1992)
Not exactly a big budget affair, Poison Ivy starred a teenaged Drew Barrymore -- now better known as Our Lady of Harmless RomComs -- as a creepy teenage stalker. It starts out as a conventional high school drama, with Ivy (Barrymore) befriending the wealthy loner Sylvie (Sara Gilbert) at school. But the friendship sours from there (perhaps her killing a dog in the first act was a sign). Ivy seduces Sylvie's father, murders her mother, and tells Sylvie they can be a family now. (That sounds completely reasonable!)
Though not a box office hit, this formula has been successful enough to spawn three -- yes! three! -- sequels, though two were direct-to-video and the third was a TV movie... which seems about right on par with the cliché quality of this bad girl flick.