The phrase "Klaatu barada nikto" originates from the 1951 cold war era science fiction film, The Day The Earth Stood Still. The phrase was used to stop Gort, the robot in the film, from attacking. There is no known translation for the phrase, although the word "Klaatu" would seem to refer to the name of the humanoid alien.

Since the term was originally used, the phrase continues to show up in popular culture. For example, the words are seen in the 1982 film, Tron, posted on a sign hanging in the hero's cubicle. Additionally, in the 1983 film, Star Wars Episode VI: Return of the Jedi; three of Jabba the Hutt's skiff guards are named Klaatu, Barada, and Nikto. In an episode of the 1987 Teenage Mutant Ninja Turtles cartoon series, three aliens encountered by Donatello and Rocksteady are named Klaatu, Barada and Nikto. In the 1992 film, Toys the character Leland Zevo speaks the phrase to stop a rampaging sea creature. In the 1993 film, Army of Darkness, the third installment of the Evil Dead triology, the hero has to speak the words in order to retrieve the Necronomicon (the Book of the Dead); he fails to remember it properly, however ("Klaatu barada .. necktie?"). In the SNES video game Lost Vikings 2 variants of the phrase were used (such as "Klatu, Veratu... Howriyucan!") as teleport spells at the end of a series of levels; like the mispoken version in Army of Darkness, they do not work quite as desired, though the correct version is eventually remembered.