Marcus Aurelius was born into a well to do, political family in southern Spain. After his father died, he was adopted by his grandfather and, after many maneuverings (from others!) and marriages and such, he became Emperor of Rome. Of all the Great Books authors, he easily gained the highest authority. He was regarded as the last of the five 'good emperors' by none other than Machiavelli and Gibbon. They ruled with 'wisdom and virtue'.
He wrote 'Meditations' while on campaign between 170 and 180 AD. While he was emperor, he fought significant wars in Parthia (Armenia and northern Iraq) and against the Germanic tribes. He died in 180 near modern day Vienna. He'd been emperor for 18 years.
The next emperor was Commodus, his son. Marcus Aurelius had been part of a line of emperors that had been placed in succession by adoption. That ended with him and Rome was worse off for it. (Commodus is the emperor portrayed in the movie Russel Crowe movie 'Gladiator', though take the history with a large grain of salt.)
'Meditations' marked Marcus Aurelius as one of the prime spokesmen for the Stoic philosophy. He was introduced to it by a teacher of his, Diognetus, early in life. He wore simple clothes and avoided the trappings of wealth.