Being stuck in a room with any one of these women would be enough to give you nightmares.
Almost all of the world's most dangerous criminals tend to be men, but what about their female counterparts?
From mafia bosses, to spies, terrorist masterminds and drug cartel warriors - we count down some of the most dangerous women in the world. Sleep tight.
1. Anna Kuschenko
According to the CIA, Anna Kuschenko - who also went by Chapman - was just six months off becoming 'the most dangerous spy in American history'.
Along with nine others, Kuschenko successfully attempted to infiltrate the upper echelons of American societal institutions, passing information on to Moscow. She married British psychiatrist, Alex Chapman, according to whom she was "conditioned" by shadowy contacts she met in London
While that alone may not be enough to scare you, Kuschenko is the daughter of a KGB official and is rumoured to have at one point been in a relationship with dictator Putin.
2. Abedo
Afghan mother-of-nine Abedo - whose full name is unknown - began fighting in the 1970s after the Soviets invaded her homeland, and is said to have made even the brutal mujahideen flinch.
Following the death of her husband the following decade, Abedo led around 200 soldiers in her continued fight. Soviet forces retreated in 1989, but she later set up her own small militia after Taliban forces set fire to her shop.
3. Samantha Lewthwaite
The world's most wanted - and likely most dangerous - woman. Dubbed by the British media as the 'White Widow', Lewthwaite is allegedly responsible for the deaths of around 400 people.
She was born in Northern Ireland before later marrying 7/7 bomber Germaine Lindsay, although her current whereabouts are unknown.
Lewthwaite has been linked to two terrorist attacks in Kenya by Al-Shabaab, including the devastating mass shooting at Nairobi's Westgate Mall in 2013.
4. Colonel Fanette Umuraza
Also nicknamed the 'Number One Queen', Congolese Revolutionary Army's second leader Umuraza is responsible for ordering mass pillages in which people are murdered in their homes and women and girls raped.
So sociopathic is she, the military leader has been known to get manicures and give interviews while her men ransack villages.
5. Marllory Dadiana Chacon Rossell
Chacon Rossell is known for her involvement in drugs trafficking, money laundering and links with Mexican cartels.
The US described her as "one of the most prolific narcotics traffickers in Central America" after her assets were frozen in 2012. She'd previously managed to oversee the transportation of thousands of kilos of cocaine from Guatemala into Mexico, and on into the States.
Her other operations in Honduras and Panama mean ruthless drugs lords in Mexico stay well-stocked.
6. Joanna Dennehy
British serial killer Dennehy is one of just three women in the country's criminal history to have received a whole life order, after Myra Hindley and Rose West.
Growing up, Dennehy's family had no clue of the frenzied violence she would later go on to commit. She was convicted in 2013 for the barbaric murders of three men in Peterborough, as well as two male dog walkers she stabbed.
The killer faces the rest of her existence behind bars. And a good thing too, after she confessed to one lover she was a "fully committed psychopath" and has been dubbed by British press as the country's most dangerous woman.
7. Maria Licciardi
Another woman on this list with an array of blood-curdling nicknames, mafia boss Licciardi had been previously given the alter-egos of "La Madrina" (The Godmother), "La Piccolina" (The Little Girl), and "The Scarlet Pimpernel of Italy".
Between 1993 and 2001, Licciardi ran the Camorra crime syndicate in Naples. She was known for the sex trafficking of many young women and girls and managed to evade police capture for years.
Her iron rule of the Camorra and its 20 different clans finally began to unravel in 1999, when a dispute over heroin culminated in a car bombing frenzy killing around 200 Neapolitans.
Cops later discovered her hideaway in the attic of a disused building, which was decked out with marble floors and an outdoor jacuzzi.
8. Enedina Arellano Felix
Another female crime lord, Enedina Arellano Felix holds the accolade of being one of the first after rising up through the ranks of a drugs cartel in Tijuana, Mexico.
According to Mexican media, her MO since being thrust into the pinnacle position has been to reduce the level of bloodshed while helping to keep her cartel's profits at a high. The gang reportedly focuses more on kidnapping than murder - so not scary at all, then.
9. Nisreen Mansour Al Forgani
Last but by no means the least terrifying, Nisreen Al Forgani has a lot of blood on her hands.
Al Forgani was a member of Muammar Gaddafi's all-female militias in Libya, and in the early days of the country's civil war, is known to have executed 11 rebels at point-blank range.
She would later go on to claim she'd been coerced into everything and sexually abused. But to escape the compound where she was supposedly forced to kill, Al Forgani later jumped from a second floor window and managed to limp away unscathed - despite being hit by a truck in the process.
