25. Dagmar Overbye
Dagmar Overbye hailed from Denmark and worked as a nanny. All her victims were children. She even killed her own. Overbye was not merciful about it either. Many of her victims suffered tremendously, and she had multiple methods of torture and killing.

Overbye did everything from strangling the children to drowning them. What she is perhaps best known for, however, is burning victims alive in her masonry burner. Reassuringly, Overbye was caught and forced to pay for her crimes. She was sentenced to death, one of three women to ever receive the death penalty in Denmark. That punishment was later dropped in favor of lifelong imprisonment.
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