Theodore Ernest Ferris (August 17, 1872 – 1953 was a naval architect and engineer responsible for the "Ferris Designs" used by the US Emergency Fleet Corporation, of the United States Shipping Board, during World War I.
Ferris was born in Stamford, Connecticut the son of Nathaniel Betts and Louise (Keeler) Ferris. He was educated in Stamford and later at the Greenwich Academy, where he took a technical training course. After a period of employment at shipyards on Long Island, he joined the Townsend-Downey Company on Shooters Island and later the firm of Cary Smith & Ferris.
In 1917, the Emergency Fleet Corporation (EFC) was established by the United States Shipping Board under General Goethals with Ferris as chief architect. His 3,500 deadweight ton "Ferris Design" wooden steamship became the model for the EFC, of which 63 were subsequently built. He also invented a system of steel strapping for fixing the frames of his ships.
Ferris married Lois Davis on August 25, 1912. They had two children, Nathaniel James and Theodore Louis Ferris.
In his obituary, the New York Times repeated an estimate that US shipyards built over 1,800 ships to his design.