Adolf Hitler (1889-1945) was a Austrian-German dictator who was leader of the Nazi Party and Head of State of Germany from 1933 to 1945. His regime of terror caused The Second World War and the Holocaust. He is seen as the symbol of evil.
Portrayal in the show
An aging version of Hitler was used during the first season of "Spitting Image" to make him have a chat with Margaret Thatcher. He offers her advice on immigration policies and she is charmed by his ideas. (Even though he is referred to as "Mr. Jeremy".)
A later sketch shows him and Benito Mussolini complaining about the comparison being made between the Nazi Party and the British Conservative Party. They write a letter claiming this is an insult to the Nazi Party.