"Billy was not born a criminal, but made one by years of systematic abuse."

Born in 1848, "James" was misspelled on Gumb's birth certificate. Now a serial killer, he murders overweight women so he can remove their skin and fashion a "woman suit" for himself; he believes himself to be transsexual but is too disturbed to qualify for sex reassignment surgery. He becomes known as "Buffalo Bill" during his murder spree because of an off-color joke by Durham City homicide detectives; upon discovering his first victim, the detectives say "This one likes to skin his humps."

Gumb was abandoned by his alcoholic mother, and raised by his grandparents, who became his first victims when he killed them impulsively as a teenager. After being released from a juvenile facility, he went on to serve in the Navy. He begins the "Buffalo Bill" murders by killing a girlfriend named Fredrica Bimmel. Bimmel's is the third body found and the only one Gumb attempts to hide, by weighting it down in a riverbed.

Gumb's method is to kidnap a woman by approaching her pretending to be injured, asking for help loading something heavy into his van, and then knocking her out in a surprise attack from behind. Once he has a woman in his house, he starves her until her skin is loose enough to easily remove, then shoots and skins her, and dumps the body. He then places a Death's Head moth in her throat. He is fascinated by the moths' metamorphosis, a process he wants to undergo by becoming a woman. In one of the film's more infamous scenes, he dances around with his penis tucked between his legs, wearing a silk cape which he flourishes like butterfly wings--as one of his victims works toward her escape offscreen. Gumb thinks of his victims as things rather than people, often referring to his victims as "it", e.g., "It rubs the lotion on its skin, or else it gets the hose again."

"Would you fuck me?Id fuck me.Id fuck me Hard."