One of my favourite movies of all time, despite the awkward title. The down-to-earth and low-budget execution works surprisingly well with the creepy and mindblowing story of individuality versus conformity.
In my book of humanity.
P.S. Fun for the whole family: Compare differences and similarities of thematic focus and handling – watch the original plus the remakes from 1978, 1993, and 2007. Interesting, and in many ways quite telling!
beyond1001movies 
The original is still my favorite. It’s a story that works beautifully in black and white. If you’ve never read it, I highly recommend the book, too.
I also like the original best, even if it might be part nostalgia.
And I actually own the book, but haven’t read it yet. But I will, any year now…