The great dictator

The Great Dictator is a 1940 American comedy-drama film starring, written, produced, scored, and directed by Charlie Chaplin, following the tradition of many of his other films. Having been the only Hollywood filmmaker to continue to make silent films well into the period of sound films, this was Chaplin's first true talking picture as well as his most commercially successful film.
At the time of its first release, the United States was still formally at peace with Nazi Germany. Chaplin's film advanced a stirring, controversial condemnation of Adolf Hitler, Benito Mussolini's fascism, antisemitism, and the Nazis, whom he mocks in the film as "machine men, with machine minds and machine hearts".
Chaplin's film followed only a few months after Hollywood's first parody of Hitler, the short subject You Nazty Spy! by the Three Stooges, although Chaplin had been planning it for years before. Hitler had been previously allegorically pilloried in the German film by Fritz Lang, The Testament of Dr.Mabuse. In his 1964 autobiography, Chaplin stated that he would not have made the film had he known about the actual horrors of the Nazi concentration camps.