Klaatu (/ˈklɑːtuː/) is a fictional humanoid alien in the 1951 science fiction film The Day the Earth Stood Still and its 2008 remake. Klaatu is famous in part because of the phrase "Klaatu barada nikto!". In the original 1951 film, Klaatu (Michael Rennie) arrives in a flying saucer in Washington, D.C., accompanied by Gort (Lock Martin), as a peaceful ambassador from an extraterrestrial confederation; but when he presents a harmless device as "a gift for [the American] President... to study life on other planets", his intentions are misinterpreted by one of the soldiers that form his welcoming committee, who shoots him. To protect Klaatu, Gort destroys the surrounding artillery. Klaatu is taken to a hospital, where he quickly recovers. On learning that the government does not expect other nations to be willing to meet him, he takes residence in a boarding house, using the surname "Carpenter", the name found on the clothes and suitcase obtained by him at the hospital, and befriends Bobby Benson (Billy Gray), a boy who stays there with his widowed mother, Helen Benson (Patricia Neal), and visits Professor Barnhardt, a brilliant scientist (played by Sam Jaffe). When Klaatu/Carpenter is brought later to him, Barnhardt agrees to summon scientists from all nations, and asks Klaatu for a show of power, thus exhibiting that the extraterrestrial alliance would threaten Earth if Earth threatens the peace in space. Klaatu, in reply, neutralizes electric power all over the world (with some notable exceptions where lives would be endangered as a result, such as hospitals and airplanes in flight) for 30 minutes. Klaatu's action is taken as an act of war. Betrayed by Mrs. Benson's suitor, he is fatally shot by the U.S. Army; whereupon Mrs. Benson, at his behest, delivers the message "Klaatu barada nikto!" barely in time to save her own life. Gort retrieves Klaatu's body, and revives him from death. Klaatu gives the assembled scientists the following ultimatum: Earth can either join other spacefaring worlds, wherein peace is ensured by a massive deterrent force of robots similar to Gort, or "be reduced to a burned-out cinder". Klaatu then departs.
