Santos Juliá Díaz (Ferrol, 1940 – Madrid, 2019) was a Spanish historian, professor of Social History and Political Thought at UNED. He stood out for his research on the social and political history of Spain in the 19th and 20th centuries, with special attention to the Second Republic, the Civil War, and Francoism. He authored numerous works, including "Historia de dos Españas", "El siglo XX en España", and biographies of Manuel Azaña. He collaborated with various media outlets and was a leading figure in the study of contemporary Spanish history. He received the National History Award of Spain in 2005.