Hitler's appropriation of Nietzsche's philosophy is well know, but what is less publicised is the support he drew from intellectuals such as Heidegger, who openly supported his campaigns. Other (non-German) philosophers spoke openly against him (notably Sartre). To what extent is philosophy open to propaganda in terms of celebrity? Other historical examples are welcomed.
Perhaps he isn't a philosopher, but I would argue Freud's understanding of psychology influenced his nephew Edward Bernays, the man who (literally) wrote the book on propaganda. I would say that Bernays has had a significant influence on marketing practices in the United States, and whether or not his methods were ultimately successful, they have had a lasting cultural impact within this particular country.
Some of the most prominent supporters of a recommendation of Adolf Hitler are: Eugen Fischer, Hans-Georg Gadamer, Martin Heidegger, Emanuel Hirsch, Wilhelm Pinder, Ferdinand Sauerbruch, Eberhard Schmidt, Friedrich Karl Schumann.
A rather complete list of the signatories including many famous philosophers and mathematicians can be found here