Oluwafemi AjayiA man who killed over 100 girls is presumed free – released by the Colombian authorities. The most dangerous people in the world earn their reputation from the sheer brutality and banality of their actions, and also from the fact that if given the opportunity, they will continue to these heinous acts.
Presently, the world’s most dangerous criminals aren’t always roaming free—they’re often locked away in high-security prisons, isolated from society but still haunting headlines and criminal psychology textbooks. These individuals have committed acts so brutal, calculated, or bizarre that their names evoke fear and fascination. From serial killers to medical professionals turned murderers, their crimes challenge our understanding of morality, mental illness, and the limits of human behavior.
What Makes Someone “Dangerous”?
Dangerousness isn’t just about body count—it’s about intent, unpredictability, and the ability to harm others even in confinement. The individuals on this list share traits that make them uniquely threatening:
- Extreme violence or sadism
- Manipulative or psychopathic behavior
- Ideological extremism
- Unrepentant attitudes
- Continued influence or threat from prison
Some are serial killers. Others are medical professionals who betrayed their oath. A few are ideologues whose crimes were meant to send a message. All are currently alive—and most are serving life sentences.
The Top 10 Most Dangerous Living Criminals in Prison (2025)
1. Rebecca Butterfield (Australia)
Known For: Murdering fellow inmate; extreme self-harm and violence
Status: Incarcerated at Silverwater Women’s Prison
Rebecca Butterfield is one of Australia’s most violent female prisoners. Diagnosed with borderline personality disorder and schizophrenia, she has a history of attacking guards and fellow inmates. In 2000, she murdered another prisoner in a brutal stabbing. Butterfield is notorious for self-harm, once carving words into her own body. Her unpredictability and aggression have led to near-permanent solitary confinement. Despite psychiatric treatment, she remains a high-risk individual whose volatility makes her a danger to anyone nearby.
2. Charles Cullen (USA)
Known For: Killing dozens of patients with drug overdoses
Status: Serving multiple life sentences in New Jersey
Charles Cullen was a nurse who used his position to murder at least 40 patients—though estimates suggest the number could be over 400. His method was subtle: administering lethal doses of digoxin or insulin. Cullen worked at multiple hospitals across New Jersey and Pennsylvania, exploiting systemic failures to avoid detection. His motive remains unclear, with theories ranging from mercy killings to a desire for control. Cullen’s case led to sweeping reforms in hospital oversight and nurse credentialing.
3. Rosemary West (UK)
Known For: Torture and murder of young women with husband Fred West
Status: Life imprisonment at HM Prison New Hall
Rosemary West, alongside her husband Fred, committed some of the UK’s most horrific crimes. Between 1973 and 1987, they tortured, raped, and murdered at least ten young women—including their own daughter. The victims were buried in the cellar and garden of their home in Gloucester. Fred died by suicide in prison, but Rosemary remains incarcerated. Her lack of remorse and role in the abuse of her children and others mark her as one of Britain’s most dangerous living criminals.
4. Joseph James DeAngelo (USA)
Known For: Golden State Killer; rapes and murders across decades
Status: Life without parole in California
Joseph DeAngelo terrorized California for decades under multiple aliases: the East Area Rapist, the Original Night Stalker, and finally the Golden State Killer. His crimes included over 50 rapes and 13 murders between 1974 and 1986. He evaded capture for years until DNA evidence linked him to the crimes in 2018. DeAngelo was a former police officer, which helped him avoid suspicion. His calculated brutality and ability to manipulate victims make him one of the most chilling figures in American criminal history.
5. Anders Behring Breivik (Norway)
Known For: Mass murder of 77 people in 2011 attacks
Status: Serving 21-year sentence (renewable indefinitely)
Breivik carried out one of the deadliest mass killings in European history. In July 2011, he detonated a bomb in Oslo and then opened fire at a youth camp on the island of Utøya, killing 77 people—many of them teenagers. His motive was ideological, rooted in far-right extremism. Breivik remains unrepentant and has attempted to use his incarceration as a platform for his views. Norway’s laws allow his sentence to be extended indefinitely, and he is held in near-total isolation.
6. Robert Maudsley (UK)
Known For: Killing fellow inmates; kept in solitary confinement
Status: Held in glass cell at Wakefield Prison
Robert Maudsley is often called “Hannibal the Cannibal,” though the cannibalism claim is disputed. He murdered four men—three of them while already in prison. His victims were all convicted sex offenders, and Maudsley claimed he was “cleaning up” the prison system. Due to his extreme danger, he is kept in a specially constructed glass cell beneath Wakefield Prison, where he has lived in solitary confinement for decades. His intelligence and cold demeanor make him a uniquely unsettling figure.
7. Pedro López (Colombia)
Known For: “Monster of the Andes”; suspected of killing 300+ girls
Status: Released in 1998; current whereabouts unknown (possibly re-incarcerated)
Pedro López is one of the most prolific serial killers in history. He confessed to murdering over 300 girls across Colombia, Ecuador, and Peru. He was convicted of 110 murders but released in 1998 after serving just 20 years. His current status is murky—some reports suggest he was re-arrested, others claim he vanished. If alive and free, López remains a terrifying threat. His crimes were methodical, targeting vulnerable children in impoverished areas.
8. Genene Jones (USA)
Known For: Pediatric nurse who killed infants with injections
Status: Serving life sentence in Texas
Genene Jones was a pediatric nurse who injected infants with drugs to induce medical crises—then “saved” them to gain praise. Tragically, many of her victims died. She was convicted of killing one child but is suspected in dozens of deaths. Jones was released briefly due to a legal loophole but re-indicted and returned to prison in 2020. Her betrayal of trust and targeting of the most vulnerable make her one of the most disturbing figures in medical criminal history.
9. Monique Olivier (France)
Known For: Accomplice to serial killer Michel Fourniret
Status: Life imprisonment in France
While Michel Fourniret died in 2021, his wife and accomplice Monique Olivier remains imprisoned. She helped lure victims—mostly young girls—into traps where Fourniret would rape and murder them. Olivier’s role was not passive; she actively participated in the planning and execution of the crimes. Her cold demeanor and lack of remorse have shocked even seasoned investigators. Olivier’s case highlights the disturbing reality of criminal partnerships and the psychological dynamics behind them.
10. Terry Nichols (USA)
Known For: Oklahoma City bombing conspirator
Status: Life imprisonment without parole
Terry Nichols helped Timothy McVeigh plan and execute the 1995 Oklahoma City bombing, which killed 168 people—including children in a daycare center. Nichols was responsible for gathering materials and building the bomb. Though McVeigh was executed, Nichols remains incarcerated. His ideological extremism and willingness to commit mass murder in pursuit of a cause make him one of the most dangerous domestic terrorists still alive.
Psychological Profiles: What Drives These Criminals?
While each case is unique, many of these individuals share psychological traits:
- Antisocial Personality Disorder: Lack of empathy, disregard for others
- Narcissism: Inflated sense of importance, need for admiration
- Sadism: Pleasure derived from inflicting pain
- Delusional Ideology: Belief in a cause that justifies violence
- Manipulation: Ability to deceive and control others
Understanding these traits helps criminologists and psychologists develop better risk assessments and prevention strategies.
Prison Conditions and Containment
Most of these criminals are held in maximum-security facilities, often in solitary confinement. Their containment involves:
- 24/7 surveillance
- Limited contact with other inmates
- Restricted access to media and communication
- Psychiatric evaluation and medication
Despite these measures, some continue to influence others—whether through letters, legal appeals, or ideological writings.
Cultural Impact and Media Fascination
These criminals have inspired:
- Documentaries and podcasts
- Books and academic studies
- Fictional adaptations
- Public debates on justice and rehabilitation
While media coverage can raise awareness, it also risks glamorizing or sensationalizing their crimes. Ethical storytelling is essential to honor victims and promote understanding.
Conclusion: The Danger Doesn’t Always End at Conviction
Incarceration may remove dangerous individuals from society, but it doesn’t erase their impact. The criminals on this list continue to shape legal reforms, psychological research, and public consciousness.
They continue to pose a threat to their fellow inmates even from the maximum security of the prisons where they are held. If they should ever regain freedom, who can tell what they will do?!