Paul Howard Douglas (March 26, 1892 - September 24, 1976) was a University of Chicago economist and Democratic United States Senator, 1949—1967, representing the State of Illinois.

Despite being a Quaker, Douglas left the University of Chicago faculty to enlist in the army at the U.S. entry into World War II. In the war, Douglas was decorated for gallantry and lost the use of one arm.

In 1948, the Chicago Democratic machine faced a blow-up of scandals. Machine leader Jacob Arvey made Douglas the party's Senate nominee in hope that the professor's sterling reputation for honest would benefit the rest of the party.

As a Senator, Douglas was one of the most passionate, though not most effective, crusaders for civil rights, and would occasionally resort to trickery to achieve his goals. In an attmept to cut short Senator Strom Thurmond's 1957 filibuster on a civil rights bill, Douglas famously offered the parched Senator orange juice, so that Thurmond would need to use the bathroom and thus leave the Senate floor, ending the filibuster. Realizing what Douglas was doing, Thrumond's aide seized the pitcher of juice out of the filibustering Thurmond's hands.

He was an advocate for public housing and opposed real estate redlining. A fateful compromise of Douglas' was his acceptance in 1949 of a provision in a public housing bill making it possible for suburbs to reject low-income housing.

In a Republican-dominated election year, Douglas lost re-election in 1966 to Charles H. Percy. After he died, his remains were cremated, and his ashes were scattered in the lagoon of Jackson Park.

Prior to his political career, Douglas helped develop the Cobb-Douglas functional form, often used for production functions in economics.