15. Nannie Doss
Nannie Doss’s criminal career spanned several decades. She is perhaps best known as the Giggling Nanny, but she earned herself several other nicknames. These included Lady Blue Beard, Lone Hearts Killer, and Black Widow. Black Widow probably best described what Doss was all about.
Doss went through several husbands and frequently ended up a widow. This was no accident. By the time of her arrest, it was discovered that Doss had killed four husbands. But her kill count was much higher, sadly. She also was responsible for the death of her mother, two of her children, a mother-in-law, and both of her sisters. She was sentenced to life in prison.