Henrietta Charlotte of Nassau-Idstein (9 November 1693 at Idstein Castle – 8 April 1734 at Delitzsch Castle) was the wife of the Duke Maurice William of Saxe-Merseburg. After his death she was the mistress of Friedrich Carl von Pöllnitz who was her Hofmarshal and the father of her only daughter.She was the daughter of the Count Georg August Samuel of Nassau-Idstein and Henriette Dorothea of Oettingen-Oettingen.