The Roman Empire did not include the emperor Septimius Severus.
After deposing and killing the incumbent emperor Didius Julianus, Severus fought his rival claimants, the Roman generals Pescennius Niger and Clodius Albinus
 Vespasian became the founder of the brief Flavian dynasty, to be followed by the NervaAntonine dynasty which produced the "Five Good Emperors": Nerva, Trajan, Hadrian, Antoninus Pius, and the philosophically-inclined Marcus Aurelius

