Marcus Aurelius Antoninus "Caracalla" (; 4 April 188 8 April 217) 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 continued to reign 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, supposedly 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.

Caracalla's reign became notable for the Antonine Constitution (Latin: Constitutio Antoniniana), also known as the Edict of Caracalla, which granted Roman citizenship to all free men throughout the Roman Empire. The edict gave all the enfranchised men Caracalla's adopted praenomen and nomen: "Marcus Aurelius". Domestically, Caracalla became known for the construction of the Baths of Caracalla, which became the second-largest baths in Rome; for the introduction of a new Roman currency named the antoninianus, a sort of double denarius; and for the massacres he ordered, both in Rome and elsewhere in the empire. In 216, Caracalla began a campaign against the Parthian Empire. He did not see this campaign through to completion due to his assassination by a disaffected soldier in 217. Macrinus succeeded him as emperor three days later.

The ancient sources portray Caracalla as a tyrant and as a cruel leader, an image that has survived into modernity. Cassius Dio (c. 155 c. 235) and Herodian (c. 170 c. 240) present Caracalla as a soldier first and an emperor second. In the 12th century, Geoffrey of Monmouth started the legend of Caracalla's role as the king of Britain. Later, in the 18th century, the works of French painters revived images of Caracalla due to apparent parallels between Caracalla's tyranny and that ascribed to Louis XVI of France (r. 17741792). Modern works continue to portray Caracalla as an evil ruler, painting him as one of the most tyrannical of all Roman emperors.

Julia Maesa (7 May before 160 AD – c. 224 AD) was a member of the Severan dynasty of the Roman Empire who was the grandmother of emperors Elagabalus and Severus Alexander, elder sister of empress Julia Domna, and mother of Julia Soaemias and Julia Mamaea. She wielded influence during the reigns of her grandsons as Augusta of the Empire from 218 to her death, especially on their elevation to emperors.Born in Emesa, Syria (modern day Homs), to an Arab family of priests of the deity Elagabalus, Maesa and her sister Domna were the daughters of Julius Bassianus. Through her sister's marriage, Maesa became sister-in-law to Septimius Severus and aunt of Caracalla and Geta, who all became emperors. She married fellow Syrian Julius Avitus, who was of consular rank. She bore him two daughters, Soaemias and Mamaea, who became mothers of Elagabalus and Severus Alexander, respectively.As one of the Severan dynasty's prominent women, Maesa sought to return to power after her sister's suicide. She was closely involved in raising her grandson Elagabalus, and after his murder, another grandson, Severus Alexander, as emperors, which resulted in the restoration of the Severan dynasty to the Roman throne after the assassination of Caracalla and the usurpation of the throne by Macrinus. Sometime after Alexander's accession, she died in Rome. She was later deified in Syria along with her sister.