James Vincent Forrestal (1892–1949) was an American investment banker and government official who served as Secretary of the Navy at the end of World War II and became the first U.S. Secretary of Defense in 1947. His name is central to the Majestic-12 story, in which disputed documents describe him as a founder of a secret committee handling recovered UFO material.

Forrestal was born in Matteawan, New York, now part of Beacon, on February 15, 1892. He attended Dartmouth and Princeton without taking a degree, served as a naval aviator in World War I and rose at the Wall Street firm Dillon, Read & Co., becoming its president by 1937. In August 1940 he became Under Secretary of the Navy, and from May 1944 as Secretary of the Navy he organized the service's vast wartime expansion and procurement. He watched the battle for Iwo Jima in 1945.

He helped shape the National Security Act of 1947, though he had opposed full unification of the armed forces, and on September 17, 1947 he was sworn in as the first Secretary of Defense, heading the new National Military Establishment as it set early Cold War policy. He resigned at President Truman's request in March 1949, was succeeded by Louis Johnson and passed away in 1949. He is buried at Arlington National Cemetery, and the aircraft carrier USS Forrestal and the James V. Forrestal Building in Washington were named for him.

The Majestic-12 documents that the researcher Jaime Shandera said he received on undeveloped film in December 1984 include a memo dated September 24, 1947, purportedly from Truman to Forrestal, authorizing the committee, and a 1952 briefing paper for Eisenhower that lists Forrestal, Vannevar Bush and ten others as members. Researchers including Stanton Friedman defended the papers. The FBI declared one "completely bogus" after the Air Force Office of Special Investigations reported in November 1988 that no such committee had been authorized or formed, and the skeptic Philip Klass found that the Truman signature on the Forrestal memo matched one on a genuine October 1947 letter. No authenticated record places Forrestal in any UFO program.

New theories in 2026 gave him other roles. A post citing Frank Joseph's book Military Encounters with Extraterrestrials said Forrestal planned as early as 1946 to lure craft into radar arrays around Los Alamos, an idea some writers apply to the 1947 Roswell event. Another post argued that a 1948 letter from the industrialist Bradley Dewey, urging him to defend the country with "very powerful radar stations," foreshadowed later claims that radar brought saucers down in New Mexico. Researchers Craig Oliver and Michael Armentor placed him with Bush, Allen Dulles and William Donovan in their account of a postwar group that handled the alleged 1933 Magenta crash retrieval. Forrestal ran the first unified defense establishment during the first years of flying-saucer reports, and that position is why accounts of a postwar cover-up so often write him into it.