Westel Woodbury Willoughby (20 July 1867 – 25 March 1945), was an American academic.
He and his twin brother to William F. Willoughby were the sons of Westel Willoughby and Jennie Rebecca (Woodbury) Willoughby. Their lawyer father had been Major in the Union Army with the New York Volunteers, and after retiring due to injuries incurred at the Battle of Chancellorsville, served as a local prosecutor, then briefly as a trial judge andon the Supreme Court of Appeals for Virginia.
Westel Woodbury Willoughby graduated with an A.B. from Johns Hopkins University in the class of 1888, continued with graduate work and received his Ph.D from Hopkins in 1891 at a time when political science was not yet recognized as a separate discipline. His degree was awarded by the combined departments of history and economics.
On 27 June 1893, he married Grace Robinson, daughter of Franklin Marvin Robinson, a prominent lawyer in Dubuque, Iowa. After practicing law for a few years with his father in Washington, D.C., Westel W. Willoughby joined the faculty at Hopkins. He moved to Baltimore's Roland Park neighborhood in Maryland along with his wife Grace and their two young children Westel Robinson Willoughby (Robinson) and Laura Robinson Willoughby.
At the urging of Professor Willoughby, Johns Hopkins created the first department of Political Science, with him as the only professor. He continued to lead this department until his retirement at the age of 65 in 1932. He helped to found the American Political Science Association and served as its 10th President. Some have referred to him as the "father of modern political science" due to his prolific publications. His first book, The Nature of the State was published in 1898. He went on to establish himself as one of the foremost authorities on Constitutional Law and the workings of the Supreme Court of the United States.