Top 10 Sci-Fi Movies?

[violet lightning]

I never heard about "The Guyver" sounds interesting....

Yeah, I figured I'd try and keep it simple and stick to hard sci-fi. (why I didn't include great movies like Pi or Andromeda Strain or Eternal Sunshine...)
"Alien" is a great example of sci-fi/horror , but still qualifies as hard science fiction.
I think we could do totally separate threads or lists for "Bad Sci-Fi Movies", "Favorite Post-Apocalyptic Sci-Fi Movies",(a good thread!), "Fave Fantasy Movies" , not to mention favorite sci-fi tv shows...

I love everyones picks and honorable mentions.
I'll toss in two more I love, "Silent Running" (already mentioned) and "Dark Star".