List of mentally ill monarchs

This article lists monarchs who were documented to have mental illness or "madness". Such allegations are not necessarily conclusive, since the documenters might have written from political biases or rumor.

Roman emperors

Justin II (c. 520 – 5 October 578, ruled 15 November 565 – 574). John of Ephesus, who suffered theological persecution under Justin, wrote that his "mind was agitated and darkened" such that he behaved at times like a wild animal. On the advice of his wife Sophia and the Senate, he adopted the general Tiberius II Constantine as his son and delegated state authority to him.

European monarchs
King Charles VI of France (1368–1422; ruled 1380–1422), known as Charles le Fou ("Charles the Mad"), suffered from bouts of psychosis, including glass delusion.
King Henry VI of England (1421–1471; ruled 1422–1461 and 1470–1471). A breakdown in 1453 caused him to neglect state affairs for more than a year. A Lord Protector was appointed on that and two subsequent occasions to govern the kingdom. The ensuing succession struggles gave rise to the Wars of the Roses.
Queen Joanna of Castile (1479–1555; ruled 1504–1555), known as Juana la Loca ("Joanna the Mad"), is believed by historians to have suffered from melancholia, psychosis or schizophrenia.
King Eric XIV of Sweden (1533–1577; ruled 1560–1568). Developed paranoia and irrational, violent streaks later in his life leading to an erratic rule and the brutal murders of several real or perceived political rivals  in the Sture Murders. Eric himself stabbed Nils Svantesson Sture to death.
King Philip V of Spain (1683–1746; ruled 1700–24, 1724–46). Suffered from intense melancholia.
King Ferdinand VI of Spain (1713–59). Like his father Philip V, suffered from melancholia.
Queen Maria I of Portugal (1734–1816; ruled 1777–1816), known as Maria, a Louca ("Mary the Mad"). Around 1790 Maria's long-expressed anxieties developed into religiously-themed delusions. Her ministers determined that she was insane and appointed her son João to govern the kingdom.
King George III of the United Kingdom (1738–1820; ruled 1760–1820) exhibited signs of mental disorder, in the form of logorrhea, as early as 1788. He fell into a profound depression after the death of his beloved Princess Amelia, and Parliament delegated his state duties to George, Prince of Wales.
King Christian VII of Denmark (1749–1808; ruled 1767–1808). Although never completely incapacitated, Christian displayed severe emotional and moral instability, and members of his court and personal staff struggled to build a functioning government around him.
King Ludwig II of Bavaria (1845–1886; ruled 1864–1886) irritated his ministers with his uncontrolled spending on magnificent castles. With no end in sight, they arranged for a panel of psychiatrists to declare him insane and installed his uncle as regent. Although the ministers were motivated by political concerns, medical explanations have been offered that include frontotemporal dementia, schizotypal personality disorder and Pick's disease.
King Otto of Bavaria (1848–1916; ruled 1886–1913) suffered from depression, anxiety and insomnia throughout his life. In 1886, the senior royal medical officer wrote a statement declaring that Otto was severely mentally ill. Otto is believed to have suffered from schizophrenia.

Middle Eastern monarchs

Nebuchadnezzar II (c. 634 BC – c. 562 BC, ruled c. 605 BC – c. 562 BC) is described in the Bible as displaying symptoms consistent with boanthropy.
Majd al-Dawla (993–1029, ruled 997–1029) was suffering from boanthropy until he was cured by Avicenna, according to Persian traditions.
Talal of Jordan (1909–1972, ruled 1951–1952) abdicated the throne after being unsuccessfully treated for schizophrenia.

East Asian monarchs

Emperor Taishō (大正天皇, Taishō-tennō, 31 August 1879 – 25 December 1926) of Japan, suffered from a variety of neurological disorders, which though at least partially physical in origin incorporated psychological elements as well. Discussion or criticism of an emperor, including that of health issues, remains a controversial subject in Japan for cultural, political, and religious reasons and is referred to as the Chrysanthemum taboo.

References 

Mentally ill
Category:Royalty and nobility with disabilities
*
Mentally ill monarchs