Emperor of
Rome, who was sixty years old when proclaimed emperor on New Year's Day, A.D. 193. He succeeded
Commodus (anyone see
Gladiator?) after Commodus'
praetorian prefect Laetus (who arranged the plot to kill Commodus, by the way) suggested that the
soldiers follow Pertinax.
Pertinax's rule was mainly concerned with repairing the damage done by Commodus to the Roman political infrastructure by removing corrupt politicians. Also, Pertinax increased military discipline. This was unpopular with the soldiery in general, and Laetus, again, came up with a plot to kill the emperor. Man, that guy really got around... For the next ninety years, it was the praetorian prefect, not the emperor, who truly ruled Rome. They'd just kill whoever wouldn't play ball and install a new puppet ruler.
Anyhow, once Pertinax's head was flung into the streets of Rome on March 28 of the same year he was proclaimed, the soldiers put the entire empire up for auction. No, seriously. A senator named Didius Julianus won the empire for 25,000 sestertii.