[Captain Peter Blood]

Okay The Day The Earth Stood Still and Forbidden Planet are what I consider classic scifi. Even the original version of The Thing was great

[Seruzawa]

Seriously there can be no such thing as the greatest any movie. How many times have those boring droning drecks, Gone with the Wind and Citizen Kane been lionized? The idea is pure solipsism.

My wife and I watch the original “The Thing” every couple of years. It still creeps us out and I’ve been reviewing it since I first saw it when it was on TV when I was 10. That is one powerful movie. Modern film makers could learn a lot about how worthless modern CGI effects can be without a good story and competent acting.

[MikelTackNailer]

To clear up 'The Thing' spoken of here...not Biden's "You know - the thing" thing when he can't recall a thing. There's three movies so far. John W. Campbell's story "Who Goes There?" was first filmed in 1951 by Howard Hawkes. "The Thing From Another World" was an allegory to the Red Scare of the time (they were right). John Carpenter's 1982 version "The Thing" remains the gold standard of practical pre-CGI special effects carried by non-stop suspense. 2011's prequel "The Thing"'s flat acting and gross-out CGI was made by people who admired Carpenter's masterpiece while failing to understand what made it one.

Freeper 'dead' mentioned Terminator 2: Judgement Day, which truly has everything great sci-fi should, but it's director James Cameron has a twofer here with "Aliens". These films are good examples of the rare sequel surpassing it's original, though many consider "Alien" the better film. Different genres/different tastes.

"Blade Runner" may well be the greatest. The attention to details, cinematography, costumes, practical effects, set designs, daring lighting choices - all in mere service to the writing and excellent actors who drove it home.