Bainbridge Colby (December 22, 1869–April 11, 1950) was an American lawyer, a founder of the United States Progressive Party and Woodrow Wilson's last Secretary of State.

Born in St. Louis, Missouri, he graduated from Williams College and Columbia Law School, and was admitted to the New York bar. He served in the New York State Assembly from 1901 to 1902, was a special assistant to the United States Attorney General in an anti-trust action in 1917, and represented the U.S. at the Inter-Allied Conference at Paris the same year. Wilson appointed him Secretary of State from March 23, 1920 and served until March 4, 1921. He supported the President's policies firmly (his predecessor Robert Lansing had not) while the President suffered from severe side effects of a series of strokes. He supported the League of Nations and established a precedent for not recognizing newly Communist Russia which remained in place until 1933. He was a partner in Wilson's law firm from 1921 until 1923 and continued with the law for the remainder of his career.