Fort Terry was a coastal fortification on Plum Island, a small island just off Orient Point, New York, United States. This strategic position afforded it a commanding view over the Atlantic entrance to the commercially vital Long Island Sound. It was established in 1897 and used intermittently through the end of World War II. In 1952, it became a military animal and biological warfare (BW) research facility, moving to civilian control in 1954 as the Plum Island Animal Disease Center. However, the biological warfare mission continued under civilian control until 1969, when the US ended offensive BW research. The island is now being considered for sale or conversion to a wildlife refuge. Fort Terry was listed on the National Register of Historic Places in 2021.