Christian August von Eyben (30 August 1700, Schleswig - 21 January 1785, Lübeck) was a German lawyer and dean of the Bishopric of Lübeck.
After a grand tour with his elder brother Friedrich, in 1723 he entered the service of the prince-bishop of Lübeck Christian August as a squire - the bishop was Laos his godfather.
He was an assessor in the Justizkanzlei, the Rentkammer and the Consistory and rose to be chief steward to Christian August's wife Albertine Friederike von Baden-Durlach - his father had entered public life in the service of Albertine's father Frederick VII, Margrave of Baden-Durlach.
In Braunschweig Cathedral in 1735 he married Elisabeth Sophia Maria von Hassberge (1717–1782).
They had eight children: Christian August and his wife were buried in a north-west ambulatory chapel in Lübeck Cathedral.