Atlantis (, "island of Atlas") is a fictional island mentioned within an allegory on the hubris of nations in Plato's works Timaeus and Critias, where it represents the antagonist naval power that besieges "Ancient Athens", the pseudo-historic embodiment of Plato's ideal state (see The Republic). In the story, Athens was able to repel the Atlantean attack, unlike any other nation of the (western) known world, supposedly giving testament to the superiority of Plato's concept of a state. At the end of the story, Atlantis eventually falls out of favor with the gods and famously submerges into the Atlantic Ocean.

Stargate Atlantis (often abbreviated SGA) is a Canadian-American adventure and military science fiction television series and part of MGM's Stargate franchise. The show was created by Brad Wright and Robert C. Cooper as a spin-off series of Stargate SG-1, which was created by Wright and Jonathan Glassner and was itself based on the feature film Stargate (1994). All five seasons of Stargate Atlantis were broadcast by the Sci-Fi Channel in the United States and The Movie Network in Canada. The show premiered on July 16, 2004; its final episode aired on January 9, 2009. The series was filmed in and around Vancouver, British Columbia, Canada.