The true story of how a mission to the moon became a mission to return three astronauts to earth alive is, to my mind, Ron Howard's best movie and the only one that has transcended the line between "pretty good" and "kind of great."
Lonely robot seeks love. Oh, and saves humanity from being permanently adrift in the vast sea of outer space.
In space no one can hear you scream... which is probably a good thing because they'd never hear anything else, judging by the events in Alien and its many successor films. With its potent mixture of sci fi and horror, Alien is one hell of a ride.
The film that launched an entertainment juggernaut and created a pop culture touchstone. Yes, The Empire Strikes Back is arguably the better narrative, but you've got to give credit to the one that started it all.
It doesn't get much better than Stanley Kubrick's dense, endlessly fascinating take on evolution (both human and technological). 2001 is a head-scratcher in parts, but it's also a work of technical perfection, a narrative marvel, and one of the greatest films ever made.