Giuseppe Giacosa (21 October 1847 – 1 September 1906) was an Italian poet, playwright and librettist,
He gained initial fame for his play Una Partita a Scacchi ("A Game of Chess") in 1871. His main field was playwriting, which he accomplished with both insight and simplicity, using subjects set in Piedmont and themes addressing contemporary bourgeois values. He wrote La signora di Challant (La Dame de Challant, The Lady of Challand), based on a novella by Matteo Bandello, for noted French actress Sarah Bernhardt, produced in New York in 1891.
Giacosa wrote the final polished version of the libretto for Giacomo Puccini's Manon Lescaut, which had been begun by Ruggero Leoncavallo, Marco Praga, Domenico Oliva, and Luigi Illica. He also wrote the librettos used by Puccini for La bohème, Tosca and Madama Butterfly in conjunction with Luigi Illica. Illica supplied the plot and dialogue, and Giacosa polished the libretto into verses.