Looking up something about the movie The Day The Earth Stood Still, I accidentally discovered that the movie was based on a short story by a writer named Harry Bates called Farewell To the Master. It was originally published in the October 1940 issue of Astounding Science Fiction and its plot is rather different from the movie.
There’s a detailed summary on the Wikipedia page, but the short short version is that a man and robot emerge from a space ship, Klaatu and Gnut, a lunatic shoots Klaatu who dies and is buried in a mausoleum, the robot stands still for a few days, then eventually retrieves Klaatu’s body and leaves, intending to make a new Klaatu.
As the robot prepares to depart, Sutherland impresses upon it the need to tell its master, the Klaatu yet to come, that his death was a terrible accident. Gnut replies, “You misunderstand, I am the master.”
In the movie, the robot Gort is very much a servant, if an autonomous servant. It was created by the peoples of the galaxy to ensure peace (by wiping out anyone sufficiently warlike). I wonder how it was the movie came to be based upon the short story. It only has a few things in common.