Fernando Claudin (1915-May 16, 1990) was a Spanish communist ideologist and historian best known for his two volume study The Communist Movement: From Comintern to Cominform.
Initially a student of architecture in his hometown of Madrid, in 1933 Claudin became so committed to the idea of political revolution that he gave up all of his own personal ambitions to join the Young Communists. Following Franco's victory after the Spanish Civil War many of those in the Spanish Communist Party lived in exile in Mexico, including Claudin himself. From 1944 to 1964 Claudin sat on the Executive committee of the Spanish Communist Party. Following the revelatory 20th Congress of the CPSU, Claudin found himself increasingly at odds with an official party line which overwhelmingly supported Soviet policies regardless of the actions of the Soviet Union itself. Despite several attempts to mend a schism in the Spanish Communist Party resulting from the fallout, Claudin was eventually expelled in 1964.
He subsequently wrote a critical Marxist history of the Soviet-aligned Communist movement La crisis del movimiento comunista. De la Komintern al Kominform (1970), which was translated into English and published as The Communist Movement: From Comintern To Cominform in 1975.