Emperors · Roman Empire Daily
In 193 AD the emperor's own bodyguard literally sold the throne to the highest bidder.
Deep dive
After murdering the emperor Pertinax, the Praetorian Guard auctioned the empire; Didius Julianus won with a huge promised payment. He lasted only about two months before being overthrown.
Source: Cassius Dio, 'Roman History,' 74.11; Herodian, 'History,' 2.6.