A Clockwork Orange, A first class dystopian jeu d'esprit to quote the author Anthony Burgess for all the the right reasons, actors, a script that takes nothing away from the novel and the sets including the Transcriptors turntable (will post an image of it soon [still in my NN's estate] it has sustained some damage over the last 50 years but still an icon) and the music. A master piece from Stanley Kubrick.
Quadrophenia, Just need to say The Who, love all versions of Tommy the album but the movie wasn't good at all.
Barbarella as with my other selection, because someone dared to make it.
There are many great dystopian movies that have been produced as a result of these but you would have to go back to Fritz Lang's Metropolis to find a movie that had the same impact on the movie making industry as these had.