Fritz Haarmann, the 'Butcher of Hanover', murdered at least 24 young men in 1920s Germany. Inside one of the Weimar era's most notorious serial killer cases.

Belle Gunness lured suitors to her Indiana farm with marriage ads, then murdered them for their money. One of America's deadliest female killers — who then vanished.

Karl Denke, the 'Cannibal of Münsterberg', murdered at least 30 travellers over two decades in 1920s Germany — a respected churchman hiding monstrous secrets.

Mohammed Bijeh was convicted of abducting and murdering around 20 children near Tehran in 2004 — a case that exposed grave failures to protect vulnerable families.

Gennady Mikhasevich, the 'Vitebsk Strangler', murdered at least 36 women in Soviet Belarus — while at least 14 innocent men were wrongly convicted for his crimes.

Tiago Gomes da Rocha, a Brazilian security guard, confessed to 39 motorcycle drive-by murders in Goiânia, targeting women, homeless people and gay men.

Yoo Young-chul, the 'Raincoat Killer', murdered 20 people in Seoul, targeting wealthy elderly couples and sex workers. One of South Korea's most notorious killers.

Carlos Robledo Puch, the baby-faced 'Angel of Death', murdered 11 people in Argentina before turning 20 — and became the country's longest-serving prisoner.

Alexander Spesivtsev, the 'Novokuznetsk Monster', preyed on street children and young women in 1990s Siberia with his mother's help. A grim post-Soviet case.

Florisvaldo de Oliveira, 'Cabo Bruno', was a São Paulo police officer turned vigilante killer accused of more than 50 extrajudicial murders in the 1980s.

Francisco de Assis Pereira, the 'Park Maniac', lured women with promises of modeling work into a São Paulo park, where he raped and murdered at least 11.

Carl Panzram confessed to 21 murders and a lifetime of crime, calling himself 'rage personified'. A brutal serial killer shaped by institutional abuse.

Bobby Joe Long murdered 10 women in Tampa Bay in 1984. A teenage survivor's courage led to his capture and, decades later, his execution.

Clifford Olson murdered 11 children and young people in British Columbia, and his shocking 'cash for bodies' deal changed Canadian criminal justice forever.

Joel Rifkin murdered at least 17 women in New York between 1989 and 1993, evading police for years until a traffic stop revealed a body in his truck.

Dorothea Puente, the 'Death House Landlady', murdered vulnerable tenants at her Sacramento boarding house to steal their benefit checks, burying them in the yard.

Anthony Sowell, the 'Cleveland Strangler', murdered 11 women at his Imperial Avenue home — a case marked by overlooked victims and ignored warnings.

Donato Bilancia murdered 17 people in just six months across the Italian Riviera in 1997–98, including victims killed on trains — Italy's most prolific serial killer.

Charles Sobhraj, 'The Serpent', is suspected of murdering more than 20 backpackers across 1970s Asia. A con man and killer who evaded justice for decades.

Henry Lee Lucas confessed to hundreds of murders — most of them lies. The true story of the 'Confession Killer' who fooled US police and closed cases falsely.