Movie that had a profound affect on you.
Lots of movies already mentioned strike a chord with me...platoon, american history x, glory, wizard of oz (scared the crap out of me when I was a very young kid).
More recently The lives of Others had a very strong impact on me. That movie actually convinced 43 Israeli elite troops to write a letter to Prime Minister refusing to continue monitoring (spying on) Palestinians who were not actually being classified as combatants
Also, Interstellar really struck a chord with me.