Vlad III Dracula—better known by the gruesome moniker “Vlad the Impaler”—was a 15th-century ruler of Wallachia (now part of Romania) who became notorious for his rampant use of torture, mutilation and mass murder. Vlad’s military exploits saw him praised by many as a hero, but his unmatched cruelty and penchant for barbaric executions—often against his own people—contributed to his reputation as one of history’s most coldblooded leaders.

Vlad’s victims were supposedly killed through unspeakable means including disembowelment, beheading and even being skinned or boiled alive. Still, his preferred method was impalement, a grisly process in which the victim had a wooden stake slowly driven through their body before being left to die of exposure. After one famous military victory against the advancing Ottoman Turks, Vlad supposedly had around 20,000 men impaled on the banks of the Danube.

When the second wave of invaders arrived, they are said to have immediately retreated upon seeing the grotesque “forest” of corpses. According to some accounts, Vlad enjoyed dining among the thousands of impaled bodies and would even dip his bread into the blood of his victims. This bizarre practice—along with the name “Dracula” and Vlad’s birthplace of Transylvania—would later partly inspire the vampire in Bram Stoker’s 1897 novel “Dracula.”

Much of Grigori Rasputin’s life is shrouded in myth, but history paints the picture of a “mad monk” who steered Russia toward chaos. Rasputin began his career as a populist holy man and was known to preach a religious doctrine arguing that true salvation was only possible through indulgence in sin. His reputation as a faith healer eventually saw him summoned to the court of Czar Nicholas II, where he ingratiated himself to Czarina Alexandra Feodorovna after helping her hemophiliac son recover from an injury. By 1911 Rasputin had secured himself a place as the czarina’s closest advisor. He then began using his influence to appoint incompetent and crooked officials while also indulging in drink and perverse sexual appetites.

Rasputin had a con man’s charm and reportedly took delight in humiliating high society women by making them lick his dirty fingers after he had dipped them in soup. He was accused of raping a nun and was known to consort with prostitutes by night even as he advised the czarina on state policy by day. Fearing that the wild-eyed sorcerer was leading Russia toward disaster, in 1916 a group of aristocratic conspirators poisoned him with cyanide. When the toxin failed to have its desired effect, the men reportedly shot him several times and then beat him before dumping his body into the freezing Neva River. Rasputin’s death ultimately came too late to save the royal family from public disgrace. The czar, the czarina and their five children were all murdered in 1918 during the Bolshevik Revolution.

Could one of America’s first serial killers also be the Ripper? No one knows for sure how many lives H.H. Holmes took, but it’s believed he was responsible for killing as many as 200 people in the late 19th century. The crowning achievement of his dark deeds was the construction of a building a hotel on Chicago’s south side that he engineered to be a factory of death, complete with a gas chamber, dissection room, trap doors and a basement furnace to destroy any trace of his sinister work.

Although Holmes was arrested, convicted and sentenced to death, some “Ripperologists” believe it wasn’t Holmes who was executed in 1896—and that his murderous spree wasn’t limited to the United States. Holmes’ own great-great grandson, Jeff Mudgett, believes his ancestor was also Jack the Ripper, based on a series of diary entries in which Holmes’ purportedly outlined his involvement in the Whitechapel murders.

Often called the “Blood Countess,” Elizabeth Báthory was a Hungarian noblewoman who is widely considered to be history’s most deranged female serial killer. Throughout the late 16th and early 17th centuries, Báthory reportedly lured young peasants to her castle with promises of high-paying jobs as servants. Once trapped in the citadel, these victims were subject to unspeakable torture. Some were beaten or stabbed with needles, while others were stripped naked and left to freeze in the snow. According to legend, Báthory even bathed in the blood of her virgin victims, believing it would keep her skin radiant and youthful.

Báthory allegedly massacred as many as 80 peasant girls—though the number may be as high as 600—but it was only when she turned her attention to young noblewomen that she was finally stopped. In 1611 she was bricked up inside her castle chambers with only a small opening for food. She would die four years later in 1614. Some historians have since argued that Báthory was framed by political enemies. While this claim is disputed, there is little doubt that her reputation has become thoroughly intertwined with myth and legend. Along with Vlad the Impaler, she is said to be one of the historical influences behind Bram Stoker’s novel “Dracula.”

In 1888, London’s Whitechapel district was gripped by reports of a vicious serial killer stalking the city streets. The unidentified madman was known to lure prostitutes into darkened squares and side streets before slitting their throats and sadistically mutilating their bodies with a carving knife. Between August and November, five streetwalkers were found butchered in the downtrodden east-end district, sparking a media frenzy and a citywide manhunt. While he was originally known simply as the Whitechapel murderer, the killer soon earned a chilling new moniker: Jack the Ripper.

Without modern forensic techniques, Victorian police were at a loss in investigating the Ripper’s heinous crimes. Eyewitness testimonies were often contradictory, and after taking his final victim on November 9 the killer seemed to disappear like a ghost. The case was finally closed in 1892, but Jack the Ripper has remained an enduring source of fascination. The most popular theories suggest that the killer’s understanding of anatomy and vivisection mean he was possibly a butcher or a surgeon. Over 100 possible suspects have been proposed, and the term “Ripperology” has even been coined to describe the extensive study the case receives.

Gilles de Rais was a 15th-century French nobleman, soldier and companion-in-arms of Joan of Arc during the Hundred Years’ War. Rais’ military career earned him many plaudits, but his distinguished reputation and opulent lifestyle hid a horrific dark side that included charges of Satanism, rape and murder. Beginning in the 1430s, Rais reportedly began torturing and brutally killing young children, many of them peasant boys who had come to his castle to work as pages. After sexually molesting these servants, Rais would murder them by cutting their throats or breaking their necks with a club. Others were decapitated and dismembered, and Rais was even known to kiss the severed heads of some of his victims.

Rais indulged in these sadistic habits unchecked until 1440 when he attacked a priest over a land dispute. This drew the ire of the church, which launched an investigation and soon uncovered the baron’s history of depravity. A famous trial ensued in which Rais was charged with murder and sodomy and accused of practicing alchemy and other satanic rites. He eventually confessed under torture to having murdered as many as 140 children—though some have claimed the number may be much higher—and was hanged to death and then burned in October 1440. Some historians have since suggested that Rais was the influence for the 17th-century folktale “Bluebeard,” which follows a wealthy baron who murders his young wives.

From 1483 to 1498, Tomás de Torquemada presided over the Spanish Inquisition, the notorious Catholic tribunal used to try heretics and nonbelievers. In order to force their confession, these victims were subjected to gruesome punishments including strangulation or being stretched on the rack. Others were waterboarded or put through strappado, a grueling torture in which subjects were hanged by their wrists until their arms were dislocated.

A Franciscan monk, Torquemada was the man responsible for reorganizing the Inquisition and expanding its scope to include crimes like blasphemy, usury and even sorcery. Torquemada also ordered the expulsion of thousands of Jews, Muslims and blacks, all of whom he believed would taint the spiritual purity of Spain. Those that converted to Christianity were allowed to remain but risked being tortured or executed if they tried to practice their faith in secret. All told, some 2,000 people were murdered during Torquemada’s reign as Grand Inquisitor, most of them beheaded or burned at the stake.