Didius Julianus was a Roman senator who won an auction to become emperor. The Praetorian Guard killed the previous emperor and then held an auction to sell the position of emperor to the highest bidder. Didius was the highest bidder. He paid his cash and became emperor on the 28th of March, 193 AD.
His reign didn't last long. The original assassination started the Roman Civil War of 193-197 and one of its first casualties was Didius only 9 weeks after he became emperor.
This is really starting in the middle though. There were a total of 5 emperors of Rome in 193 AD. You can click through to read the gripping stories of all 5, but the first one is a fantastic example of a ruler sewing the seeds of his own destruction.
Commodus became emperor in 180 AD, but his sane rule ended when a close advocate, Cleander, was assassinated. He began to fear for his life, so he started to massacre the nobles and aristocracy. His brilliant plan was to basically get rid of anyone who could possibly challenge his rule. Of course, his actions motivated those exact people to challenge his rule. Three nobles decided they're rather live than die, so they had Commodus strangled.
Rule of Rome could get pretty exciting at times. In addition to the year of the 5 emperors, there was also a year of the four emperors and a year of the six emperors.
