Alexander Severus, Marcus Aurelius (208-235), a Roman emperor, ruled 222-235. Alexander was the cousin and adopted son of Emperor Heliogabalus, whom he succeeded. Well-educated and a patron of the arts, he introduced social, economic, and administrative reforms. Alexander halted the invasion of Mesopotamia by Ardashir, king of Persia, 231-33. He attempted to check the advance of the Germanic tribes in Gaul, 234-35, but was forced to negotiate for peace. His troops mutinied, murdered Alexander, and proclaimed Maximinus emperor.