Carrie (Brian De Palma, 1976) is the quintessential horror film, opening with a scene that showcases one of its central themes: what is repressed inevitably gets unleashed.
The opening famously features Carrie (Sissy Spacek) getting her first period in the shower at gym (yes, we’re in the terrain of real horror here!). The other girls (of course) mock her, throwing pads and tampons and screaming at her to “Plug it up.” Carrie does “plug it up”—in all kinds of ways—and what she plugs up gets spectacularly released in blood and death on prom night.
The most compassionate of Carrie’s high school acquaintances, Sue (Amy Irving), survives the blood bath, however (perhaps because of her kindness)—becoming one of the first Final Girls of horror (arguably preceded only by Lila from Psycho [1960], Sally from The Texas Chain Saw Massacre [1974], and Jess from Black Christmas [1974]).