William Joseph Donovan was born in Buffalo, New York, in January 1883. He was a college football player (where he earned the nickname "Wild Bill") at Columbia University, from where he graduated in 1905. In 1912 he established, and led, a New York State National Guard cavalry troop that served in the 1916 Pancho Villa campaign on the Mexican border. In World War One Donovan served in France with the US Army's 165 Infantry (69th New York) Regiment, where he was subsequently awarded the Medal of Honor (America's highest valour award), for leading a successful assault. He reached the rank of Colonel by the end of the War and had earned the Distinguished Service Cross, and three "purple hearts".

After the end of the War he was the US Attorney for the Western District of New York and served as Assistant US Attorney General, 1924-29. He practised law in New York from 1929-41 and was Republican nominee for Governor of New York in 1932.

Before American involvement in World War II he acted as an emissary for Navy Secretary Frank Knox and President FD Roosevelt, travelling to Britain and elsewhere in Europe. In July 1941 he was appointed by Roosevelt as Coordinator of Information (COI), making him the first overall chief of the US Intelligence community. He was re-appointed by Roosevelt as Director of the Office of Strategic Services (OSS, successor to the COI) in June 1942, a post he held until October 1945. The OSS was responsible for espionage and sabotage in Europe and in parts in Asia. In March 1943 he was promoted to the rank of Brigadier General and in November 1944 to the rank of Major General. For his WWII service, Donovan received the Distinguished Service Medal, the highest US military service award.

Donovan was released from the US Army in January 1946 but served as Special Assistant to Chief Prosecutor Telford Taylor at the Nuremberg Trials. He subsequently returned to his Wall Street firm, Donovan, Leisure, Newton and Irvine. In 1949, he was appointed as Chairman of the newly-founded American Committee on United Europe, which worked to counter the perceived Communist threat to Europe by promoting European political unity. He also served as US Ambassador to Thailand in 1953/4 at the personal request of President Eisenhower.

He died in February 1959 and is buried in Arlington National Cemetery. President Dwight D. Eisenhower referred to him as "the Last Hero," which later became the title of a biography of him. He was posthumously awarded the Freedom Award of the International Rescue Committee.

He is the only American to have received his nation's four highest awards, The Medal of Honor, the Distinguished Service Cross, the Distinguished Service Medal and the National Security Medal.