João do Canto e Castro da Silva Antunes (19 May 1862, in Lisbon – 14 March 1934, in Lisbon), commonly known simply as João do Canto e Castro was a Portuguese Navy officer and the fifth president of Portugal during the First Portuguese Republic.

In 1891 he married Mariana de Santo António Moreira Freire Correia Manoel Torres de Aboim (Lisbon, 13 June 1865 – 18 January 1946), sister of the 1st Viscount da Idanha and niece of the 1st Viscount de Vila Boim, and had issue.

The first one, in Santarém, in December 1918, was led by the republicans Francisco da Cunha Leal and Álvaro Xavier de Castro.

The second one was monarchist and was perpetrated in January 1919 and organized by Paiva Couceiro, who for some time managed to control the northern part of the country in what was called the Monarchy of the North.

Although Canto e Castro was a monarchist, as President of the Republic he had to fight against a movement that defended his own ideals.