After a huge flying saucer landed on the mall in Washington, DC in 1951, a benevolent, humanoid, interplanetary alien visitor named Klaatu (Michael Rennie) who was seeking peace emerged down a ramp, followed to everyone's amazement by silent, killer bodyguard Gort - who had the ability to zap (vaporize or melt) weapons or tanks with a lethal, disintegration laser beam heat-ray behind his sliding visor. The robot, an interstellar guardian - a member of a police force, had the power to destroy worlds such as Earth, whose inhabitants were intent on destruction, aggression, and hostility. However, his main objective was to warn Earth to establish peace - and to demonstrate his power, he shut down the world's power supply (hence, the film's title "The Day the Earth Stood Still").

Czech playwright Karel Capek coined the term'robot' in post-WWI 1920 in his play R.U.R. (for Rossum's Universal Robots) that was first performed in Prague in 1921. It was taken from the Czech word'robota' meaning work, to describe humanoid androids designed for menial and repetitive labor. In the play, docile mechanical creatures with human characteristics were produced in Rossum's factory, until one scientist gave them emotions and turned them into killing machines that took over the world.