1. Nebuchadnezzar II of Babylon (604-562 B.C.)

William Blake’s painting of Nebuchadnezzar’s bout with madness.

The granddaddy of all mad kings is King Nebuchadnezzar, the Babylonian ruler whose first-person account of a seven-year descent into animal-like insanity is one of the most fascinating sections of the Old Testament book of Daniel. According to that account, the arrogant king was struck down for his disbelief in the Hebrews’ God, leaving his palace and living in the wild. The Biblical story of Nebuchadnezzar’s madness became the framework through which royal insanity was seen in the Judeo-Christian world.

2. Caligula, Emperor of Rome (A.D. 12-41)

Topping even his nephew Nero for the crown of cruelest and craziest Roman emperor, Caligula was known for his lavish projects, his sadism and his eccentricity. He once had his army construct a two-mile floating bridge so he could gallop along it on his horse. In another episode he ordered his troops to “plunder the sea” by gathering shells in their helmets. Tall and hairy, Caligula is said to have banned the mention of goats in his presence, but practiced facial contortions to better terrify his subjects. He built a lavish house for his horse Incitatus and attempted to appoint the steed to the high office of consul, though he was assassinated before he could complete the promotion.

3. Henry VI of England (1421-1471)

The subject of a three-part Shakespearean drama cycle, Henry VI was made king before his first birthday but spent his final decades battling mental illness as his kingdom lost land to France and slid into the chaos of the War of the Roses. Never a strong leader, Henry suffered his first full mental breakdown in 1453, which left him in an incommunicative stupor for more than a year. After a temporary recovery, his condition worsened in 1456 into lethargy punctuated by a routine of religious devotions. He was deposed by Yorkist forces in 1461, exiled in Scotland, briefly restored to the throne in 1470 but then reimprisoned and murdered the next year.

4. The Zhengde Emperor of China (1491-1521)

One of the most notorious rulers of the Ming Dynasty, the Zhengde Emperor was renowned for both his foolishness and his cruelty. He was fond of leading capricious military expeditions and liked to give orders to an imaginary double he called General Zhu Shou. During the first five years of his reign, he unwisely put a senior eunuch, Liu Jin, in charge of most of the affairs of state. When the two fell out five years later, the emperor ordered Liu executed by a three-day process of slow slicing (Liu succumbed on day two). Ming-era novels such as “The Zhengde Emperor Roams through Jiangnan” cast the emperor as foolish and gullible, at one point enjoying a bowl of rice gruel he believes to have been made from cooked pearls.

5. Joanna of Castile (1479-1555)

Few queens’ stories are sadder than that of “Juana la Loca,” whose family and rivals colluded to keep her confined in asylums. Born fourth in line to the throne of her parents Ferdinand and Isabella, Joanna was married off to Philip “the Handsome” of Burgundy at age 16. When a series of deaths made her heir apparent to Isabella’s throne, her husband kept her confined after her mother’s death in an attempt to press his claim (over Ferdinand’s) for the Castilian throne. After Philip’s death in 1506, Joanna’s confinement continued for another decade of her father’s regency. After Ferdinand’s death in 1516, Joanna and her teenage son Charles were made co-monarchs. From then on it was Charles who kept his mother imprisoned, creating a fictional world to keep her in isolation. When he was concerned that she might try to flee during a plague outbreak, Charles arranged for fake funeral processions to pass by her lodgings, convincing her to stay put. A group of rebels freed Joanna in 1520 and pronounced her sane and fit to rule—but changed their minds after she refused to support them instead of her son and sometime tormentor Charles.

6. Ivan the Terrible (1533-1584)

The first czar of all Russia, Ivan IV (whose nickname in Russian implies imposing or threatening more than evil) expanded Moscow’s influence into the lands of the ancient Eastern European federation known as the Kievan Rus. Ivan promulgated wide-ranging reforms, centralized administration and created the black-clad forerunners of Russia’s dreaded secret police. He took great pleasure in bringing members of the nobility to heel through torture and sadistic executions. Fed up with rule, Ivan attempted to resign in 1564 but was convinced to return a year later. He went on to create his own private fiefdom, the “oprichnina,” through which he exerted total control of as much as one-third of the Muscovite realms. In 1581 Ivan murdered his own son and heir, striking him with a pointed staff in a fit of rage. Despite his foibles, though, Ivan’s terribleness made him one of the most respected czars in Russia’s history.

7. Rudolf II, Holy Roman Emperor (1552-1612)

One of the most eccentric rulers of the European Renaissance, Rudolf II was perhaps the greatest collector of his age and an enthusiastic patron of the arts, sciences and pseudo-sciences. His castle complex at Prague featured a vast menagerie of animals, including lions, tigers, an orangutan and a live dodo bird. His cabinet of curiosities included a dizzying array of human and natural artifacts, organized by genre. Throughout his life Rudolf alternated between bouts of elation and melancholy. As a ruler, he would withdraw from court from weeks on end, or speak in an inaudible voice. He gave generous support to the astronomers Tycho Brahe and Johannes Kepler, helping to lay the foundation of the Scientific Revolution. Blessed and cursed with, as one historian put it, a willingness to believe almost everything, Rudolf was an equally enthusiastic supporter of astrologers, alchemists and mystics of every stripe.

8. George III of England (1738-1820)

Famously derided by poet Percy Bysshe Shelley as “an old, mad, blind, despised, and dying king,” George III showed his first signs of mental illness in 1765, early in his reign, but did not permanently succumb to his affliction until 1810, a year before Parliament made his son regent. George III ruled during a tumultuous era that including the American Revolution—the Declaration of Independence is addressed to him—as well as the French Revolution and the Napoleonic Wars that followed it. Some medical historians believe George’s illness, which was characterized by hallucinations, paranoia, general breakdowns and abdominal pains, was caused by the enzyme disorder porphyria, though a retroactive diagnosis remains tricky.

9. Carlota of Mexico (1840-1927)

It would be hard to imagine a stranger life than the one led by Carlota, the first and only Habsburg empress of Mexico. Born Charlotte of Belgium, she was the daughter of King Leopold I and the first cousin of Queen Victoria. At a young age she was married to Maximilian, then the archduke of Austria, and went to live with him in a castle in Italy. In 1864 a group of Mexican archconservatives colluded with France’s Napoleon III to depose the liberal president Benito Juaraz and appoint Maximilian emperor of Mexico. Maximilian and Carlota arrived in Veracruz, backed by French troops and conservative supporters, and made their way to Mexico City. For three years the royal couple did their best to win over the Mexican people, enthusiastically speaking Spanish as they promoted liberal agendas including land reform and better policies towards the country’s native communities. In doing so, though, they lost their conservative backers. After the French withdrew their troops in 1866, Maximilian and Carlota’s empire was left teetering. Carlota was sent to Europe to regain support from the French and the pope. When she failed at this she suffered a mental breakdown and was institutionalized. The reinstated Benito Juarez ordered Maximilian’s execution in 1867. Carlota lived on another six decades, never regaining her sanity and remaining sequestered in her family’s 14th-century castle in Belgium.

10. Ludwig II of Bavaria (1845-1886)

Opera fan, builder of dream palaces, spendthrift, deposed monarch and likely murder victim, Ludwig II was a prototypical “mad king” who may not have been mad at all. Today best known for Neuschwanstein, the fairy-tale palace he ordered built on a Bavarian hilltop, Ludwig was an enthusiastic patron of the arts. On ascending the Bavarian throne at 18 he quickly summoned his hero, the composer Richard Wagner, for a lengthy audience. Ludwig became one of Wagner’s main patrons, giving him funding to work on some of the era’s most renowned operas. Ludwig’s castle building left him in increasing debt, though, and in 1886 a group of conspirators filed a medical report (drafted by doctors who had never examined him) that declared the king permanently unfit to rule. The next morning Ludwig and his personal physician were found floating dead in a Bavarian lake under mysterious circumstances, lending credence to one of Ludwig’s most famous statements, “I wish to remain an eternal enigma to myself and others.”