### Instruction:
Please list all the emperors in the following passage

### Input:
The political unrest began with the murder of Emperor Commodus on New Year's Eve 192. Once Commodus was assassinated, Pertinax was named emperor, but immediately aroused opposition in the Praetorian Guard when he attempted to initiate reforms. They then plotted his assassination, and Pertinax was killed while trying to reason with the mutineers. He had only been emperor for three months. Didius Julianus, who purchased the title from the Praetorian Guard, succeeded Pertinax, but was ousted by Septimius Severus and executed on June 1. Severus was declared Caesar by the Senate, but Pescennius Niger was hostile when he declared himself emperor. This started the civil war between Niger and Severus; both gathered troops and fought throughout the territory of the empire. Due to this war, Severus allowed Clodius Albinus, whom he suspected of being a threat, to be co-Caesar so that Severus did not have to preoccupy himself with imperial governance. This move allowed him to concentrate on waging the war against Niger. Most historians count Severus and Albinus as two emperors, though they ruled simultaneously. The Severan dynasty was created out of the chaos of AD 193.

### Response:
Commodus, Pertinax, Didius Julianus, Septimius Severus, Clodius Albinus