They Live
Other John Carpenter greats are:
Escape from New York
Big Trouble In Little China
Other sci-fi greats:
THX-1138
Sleeper (also a comedy)
Brainstorm
Runaway
Total Recall
Brazil
Robocop
Minority Report
Heavy Metal (animated)
Hackers
Alien Nation
Barbarella
Westworld
Outland
Electric Dreams
War Games
Soylent Green
Logan's Run
The Last Starfighter
Starman
Stargate
Time Bandits