The history of true crime is filled with infamous names, but fame doesn’t always reflect the true scale of a killer’s crimes. Some of the deadliest serial killers in history weren’t household names — they operated in silence, preying on the most vulnerable and leaving behind staggering numbers of victims. Their crimes were often hidden in plain sight, overlooked by society, or difficult for authorities to fully uncover.

This list highlights the killers responsible for the highest known body counts, individuals whose actions shocked the world and left an indelible mark on history. Many of their victims were never found, and some cases remain unresolved to this day, a chilling reminder of how ordinary people can commit unimaginable horrors.

1. Pedro López – “The Monster of the Andes”

Estimated victims: 300+
Active years: 1969–1980s
Countries: Colombia, Peru, Ecuador

Pedro López is widely regarded as one of the deadliest serial killers in recorded history. Nicknamed “The Monster of the Andes,” he confessed to murdering hundreds of young girls across Colombia, Peru, and Ecuador. López targeted children from poor or marginalized communities, luring them with promises or gifts before strangling them. Many were buried in shallow graves, and in some cases, he returned to the same sites repeatedly.

What makes López especially chilling is the scale and duration of his crimes. His murders spanned decades and crossed borders, allowing him to evade authorities. Despite multiple convictions, he was eventually released due to legal loopholes and vanished from public record, leaving a legacy of terror that haunts South America to this day.

2. Luis Garavito – “The Beast”

Confirmed victims: 138
Suspected victims: 300+
Active years: 1992–1999
Country: Colombia

Luis Garavito, known as “The Beast,” was a predator of extraordinary cruelty. He targeted children across rural Colombia, often luring them away from home and committing brutal acts of torture and murder. Many of his victims were left in remote areas, making detection and recovery difficult for authorities.

Garavito’s crimes were meticulously planned, allowing him to operate for years without capture. His arrest in 1999 shocked the nation, revealing the staggering number of victims he had taken. Even with confirmed victims numbering 138, estimates suggest his true toll may exceed 300, cementing him as one of the deadliest serial killers in modern history.

3. Harold Shipman – “Dr. Death”

Confirmed victims: 218
Active years: 1975–1998
Country: United Kingdom

Harold Shipman, a trusted family doctor in the UK, committed murders under the guise of medical care. Using lethal injections, Shipman killed hundreds of elderly patients, often those who were most vulnerable and least likely to have their deaths questioned.

For decades, he remained undetected, his crimes blending seamlessly into the ordinary flow of patient care. The revelation of Shipman’s crimes shocked the nation and prompted widespread reforms in medical oversight. His case remains one of the most chilling examples of a serial killer exploiting trust and authority to commit mass murder.

4. Javed Iqbal

Confirmed victims: 100
Active years: 1998–1999
Country: Pakistan

Javed Iqbal preyed on homeless and runaway boys in Pakistan, luring them into his home before strangling them. To conceal his crimes, Iqbal dissolved the bodies in acid, leaving little evidence for authorities to follow.

Iqbal eventually confessed in writing, detailing his horrifying acts with disturbing clarity. He was sentenced to death but died in prison before execution. His crimes remain one of the most notorious examples of serial murder in South Asia, both for their brutality and the methodical way he sought to erase evidence of his actions.

5. H.H. Holmes

Estimated victims: 200+
Active years: 1886–1894
Country: United States

Herman Webster Mudgett, better known as H.H. Holmes, constructed his infamous “Murder Castle” in Chicago during the 1893 World’s Fair. The building contained hidden rooms, trapdoors, and gas chambers designed specifically to kill. Holmes lured victims under the guise of business, romance, or employment, then murdered them and disposed of their bodies on-site.

The true extent of Holmes’ crimes may never be known, but estimates place his victims at over 200. His case is one of the earliest and most infamous examples of a calculated, industrial-scale serial killer, blending cunning, charm, and pure malice.

Ready for More? Explore the Next Deadliest Killers

The killers on this list represent some of the darkest examples of human violence in modern history. Their crimes spanned decades, crossed borders, and exploited the most vulnerable in society. While their names are known to some, the true horror lies in the sheer scale of their actions and the countless lives forever altered or lost.

These stories serve as a stark reminder that evil can often hide behind ordinary appearances, and that vigilance, awareness, and justice are vital in preventing such tragedies from repeating. The names may shock, but the victims’ lives—and the lessons history teaches—must never be forgotten.

Curious to see more of history’s deadliest killers? Check out our collaboration with HorrorBuzz, where we reveal five additional serial killers whose crimes continue to horrify and shock investigators to this day. [Read Part Two here →Horror Buzz]