Klaatu barada nikto

Klaatu barada nikto
Script page of The Day the Earth Stood Still (1951) showing the phrase
Character	Klaatu (first) Helen Benson (second)
Actor	Michael Rennie, Patricia Neal
First used in	The Day the Earth Stood Still

"Klaatu barada nikto" is a phrase that originated in the 1951 science fiction film The Day the Earth Stood Still. The humanoid alien protagonist of the film, Klaatu (Michael Rennie), instructs Helen Benson (Patricia Neal) that if any harm befalls him, she must say the phrase to the robot Gort (Lockard Martin). In response Gort relents from destroying the Earth and resurrects Klaatu from death.

Edmund H. North, who wrote The Day the Earth Stood Still, also created the alien language used in the film, including the phrase "Klaatu barada nikto". The official spelling of the phrase comes directly from the script (as shown in the above image) and provides insight as to its proper pronunciation.

The phrase was never translated in the film and neither Edmund North nor 20th Century Fox ever released an official translation.

Near the end of the film, as Klaatu is pursued by the American military, he urges Helen Benson to memorize the phrase, saying "There's no limit to what he can do. He could destroy the Earth... If anything should happen to me you must go to Gort, you must say these words: 'Klaatu barada nikto.' Please repeat that."

Shortly after Klaatu is shot and killed. Knowing that Klaatu has died, Gort dissolves the polymer cube encasing him and disintegrates the two guards standing watch. Helen watches Gort kill the guards, then conveys Klaatu's message. Gort takes her inside the spaceship, and then retrieves Klaatu's lifeless body, which he revives.

In the 2008 remake, the line was added at Keanu Reeves' insistence. Klaatu uses it near the beginning of the film to shut down Gort, and again at the end, highly distorted and barely audible, when he stops the destruction of the Earth. Although the line can be heard in the film, it does not appear in the English subtitles.