After bungling a campaign in the east, Alexander headed to the Rhine where he was assassinated by Maximinius Thrax in 235 AD.
The History of Rome - 105- The Last Princeps
Alexander was only 13 when he ascended to the throne in 222. With the help of his mother and a few key advisers, he managed to avoid being the kind of disaster that previous teenage Emperors had been.
The History of Rome - 104- Here Comes the Sun
Elagabalus became Emperor in 218 AD at the tender age of 14. His short reign was defined by a scandalous private life and an obsession with the eastern sun god El-Gabal.
The History of Rome - 103- The Equestrian
Carcalla was killed by his Praetorian Prefect Macrinus in 217 AD. Macrinus then spent a troubled year as Emperor before the House of Severus came back to challenge his rule.
The History of Rome - 102- The Common Enemy of Mankind
Septimius Severus died in 211 while campaigning in Britain. He left the Empire to his sons, but their mutual hatred for one another meant that one of them was going to wind up dead.
The History of Rome - 101- And All Was of Little Value
After defeating Clodius Albinus, Septimius Severus turned over daily administration of the Empire to his Praetorian Prefect Gaius Plautianus, while the Emperor himself went looking for further military vicotries in Parthia.