Bailey Wallys Diffie (June 27, 1902 – January 12, 1983) was an American historian and teacher of Latin American and Iberian history who focused on Portuguese maritime and colonial history.
He was born on June 27, 1902 in Detroit, Texas, in the Red River Country, son of a small town lawyer, he grew up on a farm. Soon he learned Spanish, having studied both Spanish and history at Texas Christian University. He graduated from Southeastern Teachers College in Durant, Oklahoma, in 1923. An early interest in East Asia turned to the Iberian World in 1924. Having sailed to Europe as an apprentice seaman, he returned to TCU. In August 1927 he began to study in the University of Madrid, having spent three years in Spain and France; he received a doctoral degree in 1929. He began teaching in the City College of New York in 1930, a position he held for thirty-eight years, with visiting professorships to Yale University, New York City University and Columbia University. He began to write on history by the mid-1930s. He wrote several books and articles on Latin American and Iberian history. His historical study Latin American Civilization: Colonial Period was published in 1945. He was both professor emeritus at City College and a visiting professor at the University of California at Los Angeles.