William McDougall, English psychologist and polymath (d. 1938)
William McDougall FRS (; 22 June 1871 – 28 November 1938) was an early 20th century psychologist who spent the first part of his career in the United Kingdom and the latter part in the United States. He wrote a number of influential textbooks, and was important in the development of the theory of instinct and of social psychology in the English-speaking world.

McDougall was an opponent of behaviourism and stands somewhat outside the mainstream of the development of Anglo-American psychological thought in the first half of the 20th century; but his work was known and respected among lay people.