Carl Joachim Friedrich (/ˈfriːdrɪk/; German: [ˈfʀiːdʀɪç]; June 5, 1901 – September 19, 1984) was a German-American professor and political theorist. He taught alternately at Harvard and Heidelberg until his retirement in 1971. His writings on state and constitutional theory, constitutionalism and government made him one of the world's leading political scientists in the post-World War II period. He is one of the most influential scholars of totalitarianism.