Having lived a life characterized by poor health, overwork, gluttony, clumsiness of manner, and an unattractive appearance, Tiberius Claudius Caesar Augustus Germanicus (or Claudius) died on October 13, 54 CE, when he was 64.
Claudius most likely died from poisoned mushrooms, or less likely from a poisoned feather.
Tiberius Claudius Nero Germanicus, or Claudius, Emperor of the Roman Empire, is believed to have died by poisoning at the hands of his wife, Agrippina. However, there are also some other theories about how he died.
Read on to learn the answer to this question.
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A Brief History of Claudius
Here’s a brief history of Claudius before looking into how he died.
Born Tiberius Claudius Drusus in 10 BCE, at Lugdunum, Gaul, his parents were Antonia Minor and Drusus. This made him the first emperor born outside of Italy.
His maternal grandmother was Octavia Minor, making him the great-nephew of Emperor Augustus. He had two older siblings, Germanicus and Livilla. His father and Germanicus had commendable military reputations.
Although he was an imperial family member, his unattractive appearance and physical disability made his family keep him away from any public appearances in his early life. Through his studies, Claudius studied the law in detail and became a considerable historian. 
Fourth in line of succession after the demise of Augustus in 14 AD, Tiberius, Germanicus, and Caligula preceded him. After a few years as Emperor, Tiberius died, and Caligula succeeded as the new emperor.
In 37 AD, Caligula appointed Claudius his co-consul; it was his first public office. After four years of his horrific rule, Emperor Caligula was assassinated in 41 AD. The chaos that followed the murder made Claudius flee to the Imperial palace to hide.
Once he was found and put under protection, he was eventually proclaimed emperor by the Praetorian Guard.
As an Emperor
Despite lacking political experience, Claudius demonstrated his capability in the Roman Empire as a worthy administrator.
However, he took great pains to please the Roman Senate, owing to his accession. He intended to remodel the Senate into a more efficient, representative body, causing many to remain hostile to him.
He was under pressure to improve his military and political image. He embarked on many public works throughout his reign, both in the capital and the provinces, building roads and canals and using Ostia’s port to deal with Rome’s winter-time grain shortages.
In his reign of 13 years, Claudius visited Britain for 16 days and conquered Britannia. This was the first significant expansion of Roman rule since the reign of Augustus. The imperial civil service was developed, and freedmen were used for the day-to-day running of the Empire. 
A cabinet of freedmen was created to superintend various branches of the administration upon whom he bestowed honors. This did not sit well with the senators, who were shocked at being placed in the hands of formerly enslaved people and ‘well-known eunuchs.’
He improved the judicial system and favored a moderate extension of Roman citizenship by individual and collective grants. He also encouraged urbanization and planted several colonies.
In his religious policy, he respected tradition and revived ancient religious ceremonies, restoring lost days of festivals and removing many extraneous celebrations added by Caligula.
Since Claudius was fond of games, there were gladiatorial matches, annual games held in honor of his succession, and games held on his birthday in honor of his father. The Secular Games were celebrated (three days and nights of games and sacrifice), commemorating the 800th anniversary of the founding of Rome.
Claudius married four times – first to Plautia Urgulanilla, then to Aelia Paetina, Valeria Messalina, and finally, Julia Agrippina. Each of his first three marriages ended in divorce. 
At 58, he married Agrippina the Younger (his fourth marriage), his niece and one of the few descendants of Augustus. Claudius adopted her 12-year-old son – the future Emperor Nero, Lucius Domitius Ahenobarbus (who was one of the last males of the Imperial family).
Having already possessed wifely powers even before they married, Agrippina manipulated Claudius making him adopt her son. 
Since his marriage with his niece in AD 49 was considered highly immoral, he changed the law, and a special decree authorizing this otherwise illegal union was passed by the Senate.
What Caused the Death of Claudius?
Most ancient historians are in consensus that the death of Claudius was because of poisoning, possibly a poisoned feather or mushrooms. He died on October 13, 54, most likely in the early hours.
Claudius and Agrippina frequently argued in the last few months before his demise. Agrippina was desperate for her son Nero to succeed Emperor Claudius rather than Britannicus, who was approaching manhood.
Her motive was to ensure Nero’s succession before Britannicus gained power.
The 64-year-old Roman emperor Claudius attended a banquet on October 12, 54. His taster, the eunuch Halotus, was also in attendance. 
The cause of Claudius’ death is poisoned mushrooms, as per ancient historians Cassius Dio, Suetonius, and Tacitus. Writing in the third century, Dio details how Agrippina shared a plate of mushrooms (with one of them poisoned) with her husband.
Since she was aware of his love for mushrooms, she’s said to have approached the infamous poisoner from Gaul, Locusta, to obtain some poison. It is this poison that Agrippina used on the mushrooms that she offered Claudius.
While some say the poison in his dinner led to prolonged suffering and death, another theory says he recovered and was poisoned again.
In the second century, the historian Tacitus claims that Claudius’s personal physician, Xenophon administered a poisoned feather, leading to his death. Claudius had a feather that was used to induce vomiting. 
One of the widespread theories is that after eating the poisoned mushrooms and using the poisoned feather, he fell ill and died.
However, since Xenophon had been generously rewarded for his loyal service, there isn’t much credibility that he helped commit the murder. The physician was, more likely, testing his dying patient’s reflexes.
Seeing as Claudius was old and ill, some historians attribute this to his death rather than believing he was murdered. His gluttony, severe illnesses during his final years, old age, and Halotus (his taster), having served under Nero in the same role for a long time, provide evidence against his murder. 
Also, Halotus continued with his position when Nero succeeded as Emperor, showing that nobody wanted to get rid of him as a witness to the Emperor’s death or as an accomplice.
In Seneca, the Younger’s Apocolocyntosis (written in December 54), an unflattering satire about the Emperor’s deification, Claudius supposedly died while being entertained by a group of comic actors. This indicates that his final illness came on quickly, and for security reasons, his death wasn’t announced until the next day.
Apparently, Agrippina delayed announcing Claudius’s death, waiting for a favorable astrological moment, until word was sent to the Praetorian Guard.
He had a temple dedicated to him in Camulodunum. He was worshipped like a God in Britannia when he was alive. Upon his death, Nero and the Senate deified Claudius.
While the exact cause of Claudius’s death isn’t conclusive, going by most of the historian’s accounts, poisoning killed Claudius, possibly at the hands of his fourth wife, Agrippina.
There’s also an equally good possibility that he died a sudden death because of cerebrovascular disease, common in Roman times. Claudius was seriously ill towards the end of 52 AD and spoke of approaching death when he was 62.