Alejandro Manuel Sinibaldi Castro (1825–1896) was acting President of Guatemala from April 2, 1885, to April 5, 1885.

Of partial Italian descent, Sinibaldi Castro was a businessman who was "First Designate to the Presidency", the equivalent of Vice-President, during the presidency of Justo Rufino Barrios.

[citation needed] When Barrios was killed on April 2, 1885, in El Salvador, Sinibaldi Castro became acting president.

[1] However, given that Sinibaldi Castro had no political connections and was not in the military, he was pressured to resign within days of taking over.

[1] His successor was General Manuel Lisandro Barillas, who served as acting president, and was eventually elected as Constitutional President.