Gröpler served as the official executioner for the Prussian state across more than three decades, carrying out sentences that spanned both the German Empire and the Weimar Republic. His career of at least 144 executions, conducted primarily by axe, placed him at the intersection of bureaucratic authority and state violence during one of Europe's most turbulent periods.

Shah operated as an armed enforcer during Afghanistan's civil war, preying on travelers along the Kabul-Jalalabad road under warlord Zardad Khan — a period of near-total impunity that allowed his violence to expand into what prosecutors counted as more than twenty killings. His 2004 execution drew international attention less for his crimes than for the process surrounding it: Amnesty International raised serious concerns about a secret trial, a confession extracted under torture, and the absence of defense counsel, suggesting the proceedings served political as much as judicial ends.

What distinguished Cullen from many others cataloged here was the duration and setting of his crimes — a hospital nurse whose access to vulnerable patients, medication systems, and institutional trust allowed him to operate largely undetected across sixteen years and multiple facilities. The confirmed death toll runs to dozens, but investigators have long suggested the true number may be considerably higher, a figure that will likely never be fully established. His case prompted significant scrutiny of how healthcare institutions handle suspicions about staff, and how easily a pattern of patient deaths can be attributed to illness rather than intent.

A figure who moved from personal violence into institutional brutality, Țandără's trajectory illustrates how Romania's communist security apparatus recruited and relied on individuals whose histories of transgression made them both controllable and useful. His self-described role as a torturer — offered voluntarily in interview — sets him apart from perpetrators who denied or minimized their participation in political repression. The re-education camp system in which he operated was among the more methodical efforts to break political prisoners through prisoner-on-prisoner violence, and his position within it as both inmate and collaborator reflects the layered coercions that sustained it.

For two decades, he commanded the most significant opium production and trafficking network in the Golden Triangle, shaping the global heroin trade at its source while simultaneously positioning himself as a Shan nationalist leader. His longevity depended not just on armed force but on political flexibility — he extracted tolerance, and at times tacit cooperation, from neighboring governments even as American authorities pursued him. When he finally surrendered in 1996, it was on his own terms, with his fortune intact.

Working as a handyman gave Fyfe sustained, unremarkable access to the homes and lives of his victims — a pattern that stretched across two decades before DNA evidence finally connected him to the killings. Convicted of five murders in the Montreal area, he withheld full confessions until after his incarceration, and the true scope of his crimes remains uncertain. He is also suspected of being behind a series of violent rapes in 1980s Montreal, suggesting a longer and broader history of harm than the convictions alone reflect.

His influence operated through institutions as much as through direct action — a boarding school he co-founded became a pipeline for a network linked to some of Southeast Asia's deadliest attacks, including the 2002 Bali bombings that killed over 200 people. Intelligence agencies and the United Nations identified him as the spiritual head of Jemaah Islamiyah, a designation he contested, though his later public pledge of allegiance to ISIL's leadership underscored the ideological commitments that defined his decades of activity.