Louis de Cahusac (Montauban, 6 April 1706 – Paris, 22 June 1759) was a French playwright and librettist, and Freemason, most famous for his work with the composer Jean-Philippe Rameau. He provided the libretti for several of Rameau's operas, namely Les fêtes de l'Hymen et de l'Amour (1747), Zaïs (1748), Naïs (1749), Zoroastre (1749; revised 1756), La naissance d'Osiris (1754), and Anacréon (the first of Rameau's operas by that name, 1754). He is also credited with writing the libretto of Rameau's final work, Les Boréades (c. 1763).