On March 18, 37, the Roman Senate annulled Tiberius' will and proclaimed Gaius Julius Caesar Augustus Germanicus (aka Caligula) emperor. From the article:
"Caligula
Seen as a welcome breath of fresh air when he took the throne, Caligula’s (12 – 41 AD / Reigned 37 – 41 AD) eccentricities soon became terrifying and he was murdered after just five years in power.
After the unhappy years of purges and treason trials, Rome welcomed its new emperor. The youngest son of the war hero, Germanicus, Gaius Caesar had grown up around soldiers and his nickname, Caligula, meaning "little boots," had stuck.
High hopes
As a child, Caligula had suffered enormously. His mother had been exiled and his two elder brothers executed on flimsy treason charges. As the grown mascot of Rome's army and the only surviving son of a charismatic father, many hoped Caligula would breathe new life into Rome.
At first, Caligula lived up to expectations. He brought back many people exiled by Tiberius and ceremoniously burned the records of the treason trials held by Sejanus.
Mad or bad?
Seven months after taking power, however, Caligula fell ill. Although he recovered, he began to act very strangely. Was he mad or just pretending? Some believe that he suffered from epilepsy, but historians are divided.
Dressed in silk robes and covered in jewels, Caligula pretended he was a god. He forced senators to grovel and kiss his feet and seduced their wives at dinner parties.
Dangerous to know
Then his eccentricities became more murderous. He restored the hated treason trials of his predecessor, executing both rivals and close allies, including the head of the Praetorian Guard, his personal protection squad.
At other times, his cruelty was more random. In one instance, he was about to sacrifice an animal as a sacred offering to the gods. He raised his mallet to kill the animal and brought it down hard. At the last moment, however, he turned and struck a priest standing nearby, who died instantly.
The situation gets worse
All this time, Caligula was spending vast quantities of money. His extravagance soon emptied Rome’s treasury, which Tiberius had greatly increased. Still spending, but now short of cash, he began blackmailing leading Roman families and confiscating their estates.
In 40 AD, he led an army north into Gaul, robbing its inhabitants before marching to the shore to invade Britain. Just as the army was about to launch its attack, he ordered them to stop and gather seashells. He called these the spoils of the conquered ocean.
Meanwhile, Caligula still wanted to become a god. The same year, he ordered his statue to be erected in the Temple at Jerusalem. This would have been highly controversial in a region already prone to revolt. Luckily, Herod Agrippa, who ruled Palestine on behalf of Rome, managed to persuade Caligula to change his mind.
A solution is found
His behavior was making Caligula seriously unpopular among Rome’s elite. Plots against his life soon became commonplace. In 41 AD, four months after he returned from Gaul, he was murdered by his closest advisors, including members of his Praetorian Guard. To prevent reprisals, they also killed his wife and daughter. Dead but certainly not mourned, Caligula was succeeded by his uncle, Claudius, the most unlikely of emperors."