Known as the "Giggling Granny" for her eerily cheerful demeanor, Nannie Doss was secretly a serial killer

 Known as the "Giggling Granny" for her eerily cheerful demeanor, Nannie Doss was secretly a serial killer who had brutally murdered four husbands, two children, two sisters, her mother, two grandsons, and her mother-in-law between the 1920s and 1950s. Poison was her weapon of choice, and she snuck it into everything from moonshine to coffee to prune cakes to discreetly kill her unsuspecting victims.

After their deaths, Doss was often able to collect insurance money, and many of her fellow community members were sympathetic and supportive of the supposedly doting housewife who had experienced so much tragedy. But when one suspicious doctor decided to perform an autopsy on her final victim, her cover was finally blown.