Karl Theodor Anton Maria von Dalberg (February 8, 1744 – February 10, 1817) was Archbishop-Elector of Mainz, Arch-Chancellor of the Holy Roman Empire, Prince of Regensburg, primate of the Confederation of the Rhine and Grand-Duke of Frankfurt.
As statesman Dalberg was distinguished by his patriotic attitude, whether in ecclesiastical matters, in which he leaned to the Febronian view of a German national church, or in his efforts to galvanize the atrophied machinery of the Empire into some sort of effective central government of Germany. Failing in this, he turned to the rising star of Napoleon, believing that he had found in the truly great man, the mighty genius which governs the fate of the world, the only force strong enough to save Germany from dissolution.
By the Treaty of Lunéville in 1801, in which all territories on the left bank of the river Rhine were ceded to France, Dalberg had to surrender Worms, Constance and also Mainz. However, he retained Aschaffenburg and in 1803 gained the Reichstädte Wetzlar and Regensburg as well as the territory of the Bishop of Regensburg. Since Mainz had been annexed by France, Dalberg's Archiepiscopal see was transferred to Regensburg as well; his eastern territories became known as the Principality of Regensburg.
In 1806, he, together with other princes, joined the Confederation of the Rhine after the dissolution of the Holy Roman Empire. He formally resigned the office of Arch-Chancellor in a letter to Emperor Francis II and was appointed by Napoleon Prince primate of the Confederation of the Rhine.
In 1806, the Reichsstadt Frankfurt was included among his territories and after the Treaty of Schönbrunn, he was elevated to the rank of a Grand Duke of Frankfurt. Thereby his territories were greatly augmented, though he had to cede Regensburg to the Kingdom of Bavaria.
In 1813 he resigned from all his offices, except the archbishopric of Regensburg, in favour of Napoleon's stepson Eugène de Beauharnais, who had been heir apparent since 1810.
He died in 1817 as Archbishop of Regensburg.
Though politically Dalberg's subservience to Napoleon was resented by the following generations, as a man and prelate he is remembered as amiable, conscientious and large-hearted. Himself a scholar and author, he was a notable patron of letters, and was the friend of Goethe, Schiller and Wieland.