#1 – Pedro Alonso Lopez
Lopez is believed to be the most prolific serial killer in the world if we exclude war criminals such as Adolf Hitler and others. Lopez allegedly murdered more than 300 women in South America.
Before he would murder his young victims, he would strangle and torture them. Lopez confessed that he murdered over 300 women, but only 53 bodies of his victims were found. He now serves a life sentence in Colombia.