Adolf Hitler was the leader of Nazi Germany during World War II and one of history's most reviled dictators, unsurprisingly this would mean he was the central antagonist of almost all WW-II based media (except, of course, that controlled by the Axis Powers) - Disney was no exception to the rule and Hitler was depicted in several cartoons of the period, although the cartoons were propaganda few could argue that Hitler, even in his exaggerated and buffoonish state in Disney media, did not serve an antagonistic role both in reality and in the fictional cartoon world.
The two most famous cartoon depicting Hitler were "Education for Death" and "Der Fuehrer's Face" - each depicted Hitler and his regime as enemies of the world, though in different ways - Education for Death showed a dark and tragic tale of a young boy growing up under Hitler's tyrannical rule whilst Der Fuehrer's Face was a more bold mockery of Hitler himself and how he had enslaved the nation whilst promising them to "never be slaves".
Hitler is also depicted in a scene in the short "Reason and Emotion". He is shown with babbling dialogue, and destroying (or merely weakening) Reason by preying upon Emotion's weakness with fear, sympathy, pride and hate. Because of this, Emotion (in a Nazi superman) is stronger, as he is trying to love his country, his freedom, and his life, and just because of Hitler being the leader, he forcefully disagrees with Reason for telling him not to listen to his scary story, not to cry over his lies and calling him a liar, and even calling his proud statements "childish nonsense", causing even Reason to Heil Hitler. Also, this causes Reason to be tied to a stake and have Emotion marching when Hitler speaks his hateful speech. In some versions, that scene was cut.
In all cartoons Hitler is depicted as an all-powerful dictator yet is not seen in person (save for a parody scene in Education for Death) - instead he is seen in pictures, usually watching over the other characters and demanding the Hitler salute every time they see his image.
Although a dangerous enemy Adolf Hitler was portrayed as a buffoon by Disney, in line with the propagandist nature of the cartoons, this was especially the case in Education for Death - though any comedy value of Hitler was quickly erased when Disney showed the cruelty his regime inflicted on his own people.
Der Fuehrer's Face
Der Fuehrer's Face is one of Disney's most famous WWII cartoons and depicted Donald Duck as a reluctant Nazi living under the rule of the Nazi Party - Hitler's presence was everywhere and the dictator continually tormented Donald Duck by forcing him to give the Hitler salute every time he saw a picture of Adolf Hitler.
Donald Duck was also forced to work in a war-factory for many hours making weapons for the Nazi cause, to further torment him images of Hitler were periodically placed on the production-line: forcing him to salute Hitler whilst also struggling to keep up with the demands of the factory.
In the end however Donald Duck is free from his nightmare, which was shown to be a bad dream and he embraces a small figurine of the Statue of Liberty - grateful to be in a democratic country.
In the end of the cartoon a picture is shown of Hitler angry face, which is quickly assaulted by a rotten tomato: a bold statement by Disney of their loyalty to America and opposition to Hitler (and by extension the Axis Powers).
Education for Death
In "Education for Death" Adolf Hitler is again depicted largely through pictures - forever watching over Nazi Germany as an unseen but all-powerful force, however this cartoon also shows Hitler himself in an Aryan fairy tale: showing the tale of Sleeping Beauty as it was told by the Nazi Party, with Hitler as the "brave" Knight.
In this scene Disney portrayed Hitler as a buffoon who ranted, raved and made a fool of himself - however for the remainder of the cartoon he was back to his usual depiction as an unseen dictator, watching over his people.
Hitler's portrait would change expression dependent on his mood in this cartoon as well, such as when the Nazi School Teacher bullied a young boy and sent him to a corner, the portrait of Hitler could be seen frowning at the boy in distaste.