Dionísio Mendes de Sousa[1] (born 9 October 1940) is a Portuguese politician, writer, educator, and former president of the Legislative Assembly of the Azores.

Sousa was born in Vila de São Sebastião, Angra do Heroísmo, on the Azorean island of Terceira.

During his military service he frequented classes at the Faculty of Letters at the University of Lisbon, obtaining a licentiate diploma in philosophy.

By the 1969-70 term, he was teaching history at the secondary school Liceu Padre António Vieira and Portuguese at the Externato Séneca in Lisbon.

[5] Since 1980 Mendes has been involved in Azorean newspapers and other media, including A União, Diário Insular, Açores Expresso, Correio dos Açores, and the Projecto Autonómico de Aristides da Mota (31 March 1892)[6] In 2013, he provided the preface and edited the work Testamento Poético ("Poetic Testament") of Coelho de Sousa.