Marcus Aurelius Severus Alexander was the last Roman emperor from the Severan dynasty, ruling from 222 to 235.
Alexander was the heir to his cousin, the 18-year-old Emperor Elagabalus. The latter had been murdered along with his mother Julia Soaemias by his own guards, who, as a mark of contempt, had their remains cast into the Tiber river. Alexander and his cousin were both grandsons of Julia Maesa, the sister of empress Julia Domna, who had arranged for Elagabalus's acclamation as emperor by the Third Gallic Legion. It was the rumor of Alexander's death that triggered the assassination of Elagabalus and his mother.
Alexander's 13-year reign was the longest reign of a sole emperor since Antoninus Pius. He was also the second-youngest ever sole legal Roman emperor during the existence of the united empire, the youngest being Gordian III. Alexander's peacetime reign was prosperous. However, Rome was militarily confronted with the rising Sassanid Empire and growing incursions from the tribes of Germania. He managed to check the threat of the Sassanids. But when campaigning against Germanic tribes, Alexander attempted to bring peace by engaging in diplomacy and bribery.