Political activist Daniel Ellsberg, who leaked the 'Pentagon Papers' detailing U.S. policy in the Vietnam War, Oct. 10, 1976.
The Leak: Over the course of three months in 1969, Daniel Ellsberg, a military analyst for Rand Corporation, repeatedly slipped out of the office with classified military documents, photocopied the documents overnight, and returned them in the morning. He sent the documents — 7,000 pages in total — to the New York Times. The files detailed high-level deception via-a-vis the Vietnam War.
The Outcome: Ellsberg was sentenced to 105 years in prison for theft and espionage, but was freed after a mistrial. He later joined the lecture circuit, published a memoir, and received multiple humanitarian awards.