Clara Elisabeth, Countess von Platen-Hallermund (14 January 1648 – 30 January 1700, Schloss Monplaisir, in what is now the Von-Alten-Garten in Hannover), was a German noblewoman, most notable as the mistress of Ernest Augustus (Elector of Hanover, father of George I of Great Britain) and for her involvement in the Königsmarck affair.

Clara Elisabeth's father tried to get her and her sister Catharina positions at the French court at Versailles.

When this attempt failed, he placed them at the court of Ernest Augustus, where Clara Elisabeth served as lady-in-waiting to the Duchess Sophia and attracted the Duke's attention.

Exerting great influence on him, she had two children with him: Ernst August (1674–1726) and Sophia von Kielmansegg (1675–1717).

In spite of being the Duke's / Elector's life-long mistress, Clara Elisabeth was married to Franz Ernst, Baron / Count (Reichsgraf since 1689) von Platen-Hallermund (1631–1709).