August 1, 10 BC - October 13, 54: Age 64
Tiberius Claudius Drusus Nero Germanicus was the grandson of Mark Anthony and Octavia (Augustus Caesar's sister) on his mother's side, and of Livia (Augustus' third wife) on his father's side. His strong connections with the imperial family of Rome would have marked him for untimely death but for one thing: he was considered an idiot and a cripple.
Claudius had some kind of physical ailment — it may have been cerebral palsy, Tourette's syndrome, or polio — but there was nothing whatever wrong with his intellect. His knees were weak, his head shook, he stammered and slobbered when excited, and he had a peculiar voice. In materialistic Rome, beauty was thought to reflect inner virtue and intelligence, and physical defects reflected moral and intellectual lacks. This certainly saved Claudius from the many purges of eligible and well-connected males undertaken by Augustus, Tiberias, and Caligula and their allies. His own mother despised him, and made no secret of it. As a youngster his family hired a mule-driver to babysit him, on the assumption that his afflictions were the result of a stubborn and dull temperament.
But Claudius was by no means an idiot. In later life he admitted to having exaggerated his defects as the perfect disguise to defend himself; he could not, however, hide his intelligence from everyone: the historian Livy and the philosopher Athenodorus tutored him as a teenager. He undertook to write a history of the Civil Wars, and this nearly undid him: they were a bit too accurate. Fortunately his mother and his grandmother Livia saw the danger and put a stop to it. This incident presumably confirmed their assumption that he was unfit for public office.
Augustus died when Claudius was 24. The succeeding emperors, Tiberius (his uncle) and Caligula (his nephew), set about destroying every other male member of the imperial family in their purges — except Claudius. In 41, Caligula was assassinated, and the conspirators began to search Rome in order to kill members of the imperial family. Claudius took refuge in the palace, hiding behind some curtains, where a guard named Gratus found him and spirited him away to safety. After some debate, the Senate agreed to accept him as the new Emperor.
Then followed, contrary to nearly everyone's expectations, 13 years of sober and conscientious rule and a period of peace and expansion that must have been a great relief after the chaotic years of Caligula's mad rule. It would have been longer, but Claudius died, probably poisoned, in 54.
Accounts of the time agree that it was likely a dish of mushrooms that delivered the fatal dose. It is generally accepted that the instigator of the poisoning was his wife, Agrippina, whose son Nero was poised to succeed his stepfather. For several months before his death Claudius and Agrippina had argued a lot, and Claudius had been showing signs of raising his own 13-year-old son Britannicus to a status higher than that of Nero (in ancient Rome it was not uncommon for stepchildren to be favoured over natural children, particularly if there were residual bad feelings about the natural child's mother). To Agrippina and Nero, it was important that Claudius die before Britannicus grew any older.
Claudius was immediately deified by Nero. Seneca, an enemy whom Claudius had banished in 41, wrote the satire, Apocolocyntosis divi Claudii (The Pumpkinification of the Divine Claudius) a few months after his death ("apocolocyntosis" is a mangling of the word "apotheosis", meaning deification). Seneca writes of his last words as follows: "This was the last utterance of his to be heard among men, after he let out a sound from that part with which he found it easier to communicate, 'Oh I think I have shit myself.'" Seneca goes on to remark, "He certainly shat up everything else." On the whole, however, most of his contemporaries and virtually all historians judge Claudius to have been a popular and competent ruler.
Sources: Wikipedia, The Journal of the Royal Society of Medicine