Francis Beverley Biddle (May 9, 1886 – October 4, 1968) was an American lawyer and judge who was Attorney General of the United States during World War II and who served as the primary American judge during the postwar Nuremberg trials.

Biddle was one of four sons of Algernon Biddle, a law professor at the University of Pennsylvania of the Biddle family. He was also a great-great-grandson of Edmund Randolph, and a half second cousin four times removed of James Madison. He was born in Paris while his family was living abroad. He graduated from the Groton School, where he participated in boxing.

He earned degrees from Harvard University in 1909 (A.B.) and 1911 (law degree). He first worked as a private secretary to Supreme Court Justice Oliver Wendell Holmes, Jr. from 1911 to 1912. He spent the next 27 years practicing law in Philadelphia, PA. In 1912, he supported the presidential candidacy of former U.S. President Theodore Roosevelt's renegade Bull Moose Party. He was also in the United States Army in 1918, during World War I. He served as special assistant to the U.S. attorney of the Eastern District of Pennsylvania from 1922 to 1926.

Beginning in the 1930s, Biddle was appointed to a number of important governmental roles. In 1934 President Franklin D. Roosevelt nominated him to be chairman of the National Labor Relations Board. On February 9, 1939, Roosevelt nominated Biddle to the United States Court of Appeals for the Third Circuit, to a seat vacated by Joseph Buffington. Biddle was confirmed by the United States Senate on February 28, 1939, and received his commission on March 4, 1939. He only served one year before resigning on January 22, 1940, to become the United States Solicitor General. This also turned out to be a short-lived position when Roosevelt nominated him to the position of Attorney General of the United States in 1941. During this time he was also chief counsel to the Special Congressional Committee to Investigate the Tennessee Valley Authority, from 1938 to 1939, and director of Immigration and Naturalization Service at the U.S. Department of Justice in 1940.

At President Harry S. Truman's request, he resigned after Roosevelt's death. Shortly after, Truman appointed Biddle as a judge at the International Military Tribunal at Nuremberg. Biddle's successor, Tom Clark told the story that Biddle, who wore spats, was the first government official whose resignation Truman sought, and that it was quite a difficult task. Biddle was amused by Truman's stammering , but after it was over, he threw his arm around the President and said, "See, Harry, now that wasn't so hard."

In 1947, he was nominated by Truman as the American representative on the United Nations Economic and Social Council. However, after the Republican Party refused to act on the nomination, Biddle asked Truman to withdraw his name.

In 1950 he was named as chairman of the Americans for Democratic Action, a position he held for three years; then one decade later, wrote two volumes of memoirs: A Casual Past in 1961 and In Brief Authority the following year. His final position came as chairman of the Franklin D. Roosevelt Memorial Commission, which he resigned in 1965.

Biddle's writing skills had long been in evidence prior to the release of his memoirs. In 1927, he wrote a novel about Philadelphia society, "The Llanfear Pattern." In 1942, he took advantage of his close association with Oliver Wendell Holmes 30 years earlier with a biography of the jurist, Mr. Justice Holmes, then wrote Democratic Thinking and the War two years later. His 1949 book, The World's Best Hope looked at the United States' role in the post-war era.

Biddle was married to the poet Katherine Garrison Chapin. He died of a heart attack in Wellfleet, Massachusetts, on October 4, 1968. He had two sons, Edmund Randolph Biddle and Garrison Chapin, and was the subject of the 2004 play Trying by Joanna McClelland Glass, who had served as Biddle's personal secretary from 1967 to 1968.