Wiliam Dawson Jr. (August 11, 1885 – July 3, 1972) was a career United States diplomat.
He was born at Saint Paul, Minnesota, on August 11, 1885, the son of William Dawson and Maria Rice.
After graduating from the University of Minnesota in 1906, he attended the Ecole Libre des Sciences Politiques in Paris and soon after entered the United States Foreign Service.
Dawson was consul-general at large from 1922 to 1924 and served as chief instructor at the Department of State's Foreign Service School from 1925 to 1928.
After retiring in 1946 he served as advisor on Latin American affairs to the U.S. delegation during the formation of the United Nations, went to Brazil on a special mission with General George Marshall and became the first U.S. ambassador to the Organization of American States.