Which emperor was appointed by the Praetorian Guard after buying the throne at auction? (r. 193 AD)

The story behind the answer

Didius Julianus is correct: after the Praetorian Guard murdered Pertinax in 193 AD, they literally auctioned the empire from their camp walls. Julianus outbid Pertinax’s father-in-law by promising a huge donative to each guardsman, and the Guard proclaimed him emperor—an infamous low point in Roman politics during the “Year of the Five Emperors.”

His “bought” reign lasted barely nine weeks before Septimius Severus marched on Rome; the Senate abandoned Julianus, and he was executed. To remember: J for “Jackpot”—Julianus won the Praetorians’ auction. By contrast, Pertinax was the reformer they killed, Commodus died before this crisis, and Septimius Severus took power by force, founding the Severan dynasty.