Karl August, Grand Duke of Saxe Weimar Eisenach

Karl August, Grand Duke of SaxeWeimarEisenach was a Duke of SaxeWeimar and of SaxeEisenach from 1758, Duke of SaxeWeimarEisenach from its creation in 1809, and grand duke from 1815 until his death. He is noted for the intellectual brilliance of his court.

In addition, Karl August acknowledged five children by him born out of wedlock

Source: Wikipedia