Publius Helvius Pertinax (/ˈpɜːrtɪnæks/ PER-tin-ax; 1 August 126 – 28 March 193) was Roman emperor for the first three months of 193. He succeeded Commodus and became the first ruler of the turbulent Year of the Five Emperors.
The son of a freedman, Pertinax rose from modest origins through a military career. He distinguished himself in the Roman–Parthian War of 161–166 and went on to hold a succession of governorships and senior commands. He also sat in the Roman Senate, where he was a contemporary of the historian Cassius Dio.