Frank the Bunny, Donnie Darko
Donnie Darko was one of those movies that stuck with me the very first time, but I wasn't sure why. I wasn't exactly clear on what happened, but I had a theory or two. I knew that somehow Donnie had done something important.
I like it when movies reward you for thinking. Only after a lot of thought and some re-watching do I now have an idea of what was going on - at least I'm pretty sure.
A couple of other things about it make it really memorable - The music was amazing, especially that haunting version of "Mad World". And who could forget Frank the Bunny? "Why are you wearing that stupid 'man' suit?"