Pertinax was Roman Emperor
Roman Emperor
The Roman emperor was the ruler of the Roman State during the imperial period . The Romans had no single term for the office although at any given time, a given title was associated with the emperor...

 for three months in 193. He is known as the first emperor of the tumultuous Year of the Five Emperors
Year of the Five Emperors
The Year of the Five Emperors refers to the year 193 AD, in which there were five claimants for the title of Roman Emperor. The five were Pertinax, Didius Julianus, Pescennius Niger, Clodius Albinus and Septimius Severus....

. A high ranking military and Senatorial figure, he tried to restore discipline in the Praetorian Guards, whereupon they rebelled and killed him. Upon his death he was succeeded by Didius Julianus
Didius Julianus
Didius Julianus , was Roman Emperor for three months during the year 193. He ascended the throne after buying it from the Praetorian Guard, who had assassinated his predecessor Pertinax. This led to the Roman Civil War of 193–197...

, whose reign was similarly short.
His career before becoming emperor is documented in the Historia Augusta and confirmed in many places by existing inscriptions.