The title duc de Brancas may refer to a number of hereditary office-holders under the Ancien Régime of France.
The most famous holder of that title was a member of the social circle of Philippe II, Duke of Orléans, who served as Regent of France from 1715 to 1723.
[1] Despite his high title, Brancas was not wealthy, but he solidly refused to exploit his relationship with France's regent in return for financial gain.
Such a lack of corruption was rare at the time, and put the family in strained circumstances.
[2] When Brancas reached the age that he had to pay young men to sleep with him, he decided to give up on secular life and retired to a monastery.