The brassy-breasted tanager (Tangara desmaresti) is a species of bird in the family Thraupidae. It is endemic to Brazil. Its natural habitat is subtropical or tropical moist montane forests.
The brassy-breasted tanager was first described as Tanagra Desmaresti by Louis Pierre Vieillot in 1819 on the basis of a specimen from Brazil. The generic name Tangara is from the Tupàword tangara, meaning 'dancer'. The specific epithet desmaresti is a patronym in honor of Anselme Gaëtan Desmarest, who wrote the book Histoire des Tangaras.