Suetonius
Suetonius was born when Vespasian was emperor, so scholars say he must have been born before 79 c.e.  His father was from Rome's equestrian social class.  He worked as a secretary for Emperor Hadrian but he was accused of something having to do with the empress Sabina and was forced to retire in 121 c.e.  He wrote De Vita Caesarum after that.