Psycho (1960), The Texas Chainsaw Massacre (1974), and The Silence of the Lambs (1991)
There's no one who's been more influential to the horror genre than Edward Gein. Gein never wrote a screenplay, or directed any features. He never acted, he didn't do makeup. No, Edward Gein was a serial killer; he provided the inspiration for the following characters: Norman Bates in Psycho, Leatherface in The Texas Chainsaw Massacre, and Buffalo Bill in The Silence of the Lambs.
In 1957, the Plainfield, WI, native confessed to a pair of murders, saying that he killed two local women over a three-year span. When the authorities searched his home, they discovered a treasure trove of horror: chairs covered with human skin, bowls made from skulls, four loose noses, the two victims' severed heads in bags, a belt made from nipples, a lampshade made from a person's face, and 10 heads with the tops cut off, amongst other grotesqueries. OK, one more, for good measure: They also found nine vulvae snipped off and placed in a shoe box.
So, yeah, there's your Chainsaw Massacre connections. As for Psycho and Silence of the Lambs, it was discovered later that, after Gein's abusive mother passed away, he started creating a "woman suit" (i.e., female skin taken from bodies that he'd tanned) so that he could give himself a makeshift sex change.