Barbara Strozzi (also called Barbara Valle) (Baptised August 6, 1619, Venice - November 11, 1677, Padua) was an Italian Baroque singer and composer. She was the adopted, and most likely illegitimate, daughter of Giulio Strozzi. Giulio incorporated her into his series of discussion groups, or academies, particularly the "Accademia degli Unisoni", wherein she was both called upon to sing, and to contribute to the discourse. Her father arranged for her to study with composer Francesco Cavalli.

Until recently, it was believed that Strozzi was a courtesan, since she was unmarried and since her relationship to her father's friends in the Accademia degli Unisoni was referred to as licentious. However, evidence that at least three of her four children were fathered by the same man (Giovanni Paulo Vidman) indicates that she was probably his paramour, or mistress, at least while he was alive. After his death it is likely that Strozzi supported herself by means of her savvy investments and by her compositions. Although she dedicated her publications to several important figures, including Ferdinand II of Austria and Sophia, Duchess of Brunswick and Lüneburg, there is no evidence that these "patrons" directly supported her.

Strozzi is unique among both male and female composers for publishing her works in single-composer volumes, rather than in collections. Her output is also unique in that it is comprised entirely of vocal chamber music, rather than opera or instrumental music. She published, if not composed, more in this genre than any other composer of her time. In addition to composing, Strozzi was considered to be a virtuosic singer.

The vast majority of her works are for Soprano and continuo, suggesting that they were written for Strozzi herself to sing. Her compositions are firmly rooted in the seconda prattica tradition, exemplified in the works of Claudio Monteverdi, but her works have a more lyrical emphasis, based in the strengths of the voice itself. Many of the texts for her early pieces were written by her father Giulio. Other texts were written by her father's friends, and possibly by herself.