Just a note, the following contains spoilers for the Quentin Tarantino film "Inglourious Basterds". Just thought I'd warn you.
Anyway, in the film, there's a small group of American soldiers dropped into occupied France a significant period of time before D-Day, where they start acting as a guerrila force. Later in the movie, they become part of a plot to kill Hitler and a great portion of the German High Command during the screening of Goebbels' latest propaganda film.
Despite being a WWII-based film, historical accuracy is the least of Tarantino's concerns - thus, the plot actually succeeds, and Hitler, along with 300 or so of his most important associates, generals and officials, are killed - including Goebbels, Göring and Bormann.
So, let's say that, in June of 1944, Hitler, Bormann, Göring and Goebbels are assassinated simultaneously. It doesn't need to be carried out exactly the way it was in the film, there just needs to be a successful co-ordinated assassination against these four key figures. Bonus points if you wipe out some other important individuals, however.