Maria Antonia von Branconi, née Elsener (27 October 1746 in Genoa – 7 July 1793 in Abano) was the official royal mistress of Charles William Ferdinand, Duke of Brunswick-Wolfenbüttel between 1766 and 1777.

At the age of twelve, she married the royal official Francesco de Pessina Branconi (d. 21 October 1766), with whom she had one daughter and one son.

In November 1766, she met the heir of the throne of Brunswick, who made a study trip through Europe after his marriage in 1764.

The relationship with Charles was ended in 1777, when he began an affair with Baroness Luise Henriette von Hertefeld (1750-1806), maid-of-honor to his aunt the queen of Prussia.

Branconi was acquainted with the professors at the university of Brunswick, among them JJ Eschenburg and Johann Arnold Ebert.