The Day the Earth Stood Still (1951)
The Day the Earth Stood Still is an exemplary example of Cold War jitters. Made in 1951, based on the story "Farewell to the Master" (the particulars of which I can remember very little about at this point), it begins with a glowing "flying saucer" with a classic look, landing on the Washington Mall. A ramp cooly slides from the surface, as the military and curious onlookers surround the alien craft. A being in a weird silver suit and a helmet covering its face points a weird object with a springy antenna at the crowd, but is promptly shot by some Army grunt and falls to the ground. His robot, Gort, a hulking mass of Fifties sci-fi aluminum comes to life, and strides like Karloff's Creature down the ramp. A visor slides back, and a ray beam melts the grunts' rifles.