Maria Teresa de Mascarenhas Horta Barros (born 20 May 1937, Lisbon) is a Portuguese feminist poet, journalist and activist. She is one of the authors of the book Novas Cartas Portugesas (New Portuguese Letters), together with Maria Isabel Barreno and Maria Velho da Costa. The authors, known as the "Three Marias," were arrested, jailed and prosecuted under Portuguese censorship laws in 1972, during the last years of the Estado Novo dictatorship. The book and their trial inspired protests in Portugal and attracted international attention from European and American women's liberation groups in the years leading up to the Carnation Revolution.