Marcus Aurelius Antoninus (born Lucius Septimius Bassianus, 4 April 188 – 8 April 217), better known by his nickname "Caracalla" (/ˌkærəˈkælə/) was Roman emperor from 198 to 217. He was a member of the Severan dynasty, the elder son of Emperor Septimius Severus and Empress Julia Domna. Proclaimed co-ruler by his father in 198, he reigned jointly with his brother Geta, co-emperor from 209, after their father's death in 211. His brother was murdered by the Praetorian Guard later that year, under orders from Caracalla himself, who then reigned afterwards as sole ruler of the Roman Empire. Caracalla found administration to be mundane, leaving those responsibilities to his mother. Caracalla's reign featured domestic instability and external invasions by the Germanic peoples.