Klaatu's Species

"We have come to visit you in peace, with good will."

- Klaatu upon arriving to Earth

This humanoid race seems to be outwardly Human in appearance. Its only known member is Klaatu, whose spaceship landed on Earth, in the United States, to deliver a message to humanity.

Biology
In terms of appearance, this species seems to be almost identical to Humans. It's been suggested that this is due to their homeworld's atmosphere being identical to Earth's. However, Klaatu's species can live much longer than Humans due to their advanced technology.

Culture and society
Klaatu's Species wants to impose security in all planets and for this they have an organization for the mutual protection of all planets in which a race of robots patrols all planets keeping peace and eliminating aggression. Any planet that doesn't join this organization and extends its violence outside of its own planet is destroyed.

Appearances

 * "Farewell to the Master" by Harry Bates (1940)
 * The Day the Earth Stood Still (1951)
 * The Day the Earth Stood Still (2008)