When it comes to time travel movies, which one...

Last Year at Marienbad.

That's more of an oneiric movie. I meant movies where we actually see the characters travelling through time. For example, 12 MONKEYS and LOOPER. They're designed to give headaches.

I guess It's A Wonderful Life kind of qualifies. We, the audience are taken back through time to witness all the frustration suffered by the main character and then are presented with an alternative present had said character existed to endure those frustration. Remember it being a bit of a mindbender when I first saw it.

@Twitzkrieg - Glasgow's FOREMOST authority

Slaughterhouse 5

Really? That's the one? Too bad I didn't like it.

You should check out "Primer", not the first one, but excellent in terms of paradoxes and mindfùcking.

For major American films, maybe Planet of the Apes (1968). Definitely a mindbender, especially at that time.

I agree there. There is nothing new under the sun. But at least for my generation, "Planet of the Apes" was most certainly the first in that area. When I see the newer versions of the same theme, I see fancier special effects, but that's about it.

Special effects that get people thinking "how'd they do that?" is one thing. But a plot line that gets people thinking really profound things like "do we even want to have a technology like that if it was dropped in our laps?" is working on a whole different level.