Aelius Caesar in the context of Caesar (title)

Marcus Aurelius Antoninus (/ɔːˈriːliəs/ or-EE-lee-əs, Latin: [ˈmaːrkʊs au̯ˈreːli.us antoːˈniːnʊs]; 26 April 121 – 17 March 180) was Roman emperor from 161 to 180 and a Stoic philosopher. He was a member of the Nerva–Antonine dynasty, the last of the rulers later known as the Five Good Emperors and the last emperor of the Pax Romana, an age of relative peace, calm, and stability for the Roman Empire lasting from 27 BC to 180 AD. He served as Roman consul in 140, 145, and 161.

Marcus Aurelius was the son of the praetor Marcus Annius Verus and his wife, Domitia Calvilla. He was related through marriage to the emperors Trajan and Hadrian. Marcus was three when his father died, and was raised by his mother and paternal grandfather. After Hadrian's adoptive son, Aelius Caesar, died in 138, Hadrian adopted Marcus's uncle Antoninus Pius as his new heir. In turn, Antoninus adopted Marcus and Lucius, the son of Aelius. Hadrian died that year, and Antoninus became emperor. Now heir to the throne, Marcus studied Greek and Latin under tutors such as Herodes Atticus and Marcus Cornelius Fronto. He married Antoninus's daughter Faustina in 145.