José da Costa e Silva (25 July 1747 – 21 March 1819) was a Portuguese architect. His work helped establish Neoclassical architecture in Portugal and colonial Brazil. Costa e Silva studied architecture in Rome, where he had contact with Italian Neoclassicism. He later became Royal architect, and headed several important projects in Portugal. Among his most important works are the Royal Theatre of São Carlos (1792) in Lisbon and the Military Hospital (1792) near Torres Vedras. He is also believed to be the author of Seteais Palace (1801) in Sintra. In Lisbon, Costa e Silva and the Italian Francisco Xavier Fabri created the project for the Royal Palace of Ajuda (after 1802), which was however too grandiose and could not be completed.