Nuno Xavier Daniel Dias (13 September 1940 – June 1976) was a São Toméan aerospace engineer and politician who served as the first President of the Constituent Assembly after the country's independence from Portugal.

[4] He served in the government as Minister of International Coordination and was the first São Toméan to have the position of head of the country's Civil Aeronautics Service.

[4] He led the construction of bridges, roads, and in his position with the Civil Aeronautics Service, he helped expand the runway of the São Tomé International Airport.

[3] At the start of July 1975, parliamentary elections were held for members of the Constituent Assembly and Xavier ran under the MLSTP party, winning a seat.

[3] A few days later, as president of the Assembly, on 12 July 1975, he signed the treaty with Portuguese officer António Alva Rosa Coutinho that established São Tomé and Príncipe as an independent nation.