Humanoid Alien (The Twilight Zone)

The humanoid aliens are seen at the end of The Twilight Zone episode, "The Monsters Are Due On Maple Street". At some point in the 1960's, they visited Earth for reasons that are not entirely clear. They seem to have been conducting a secret experiment on humanity, as they can be seen monitoring the town of Maple Street in which the story takes place.

Their experiment consisted of shutting off power across multiple towns, including Maple Street, cutting off their communications to the outside world, and observing the results. As can be seen in the episode, the results were not in humanity's favor, as, according to the aliens, the people of the towns consistently turned on each other upon losing power. Seemingly disappointed by these results, the aliens boarded their ship and left Earth.