Over a span of roughly two years, Huang Yong targeted vulnerable young men seeking employment or educational opportunities, exploiting economic precarity to lure victims into a setting from which they had no escape. His case is notable for the methodical nature of the killings, the extended duration over which they occurred, and the scale of the confirmed and suspected victim count — which may have reached 25. He was ultimately undone by a survivor who, against considerable odds, persuaded him to allow a witness to walk away. The case was resolved with unusual speed: arrest, conviction, and execution all fell within a single month.

Spain's first recorded serial killer, Romasanta is a singular figure in criminal history — not only for the murders themselves, but for the defense he offered at trial: that a curse had transformed him into a wolf, absolving him of responsibility. The werewolf claim, unusual even by the standards of 19th-century rural superstition, drew enough attention that a royal pardon was briefly considered on medical grounds. His case sits at an intersection of folklore, early forensic history, and the judicial reckoning with what courts owed to confessed killers who rejected their own agency.

A career soldier whose crimes extended well beyond his single conviction, Chanal became the focus of investigations linking him to the disappearances of several young male hitchhikers in northeastern France during the 1980s — a series of cases that remained unresolved at the time of his death. His military background and the prolonged uncertainty surrounding the full scope of his actions made him a troubling figure in French criminal history, and the cases he was suspected of are still among the country's most haunting unsolved disappearances.