The story of Stargate SG-1 begins about a year after the events of the feature film, when the United States government learns that an ancient alien device called the Stargate can access a network of such devices on a multitude of planets. SG-1 is an elite Air Force special operations team, one of more than two dozen teams from Earth who explore the galaxy and defend against alien threats such as the Goa'uld, Replicators, and the Ori.

Babylon 5 is a five-mile long space station located in neutral space. Built by the Earth Alliance in the 2250s, its goal is to maintain peace among the various alien races by providing a sanctuary where grievances and negotiations can be worked out among duly appointed ambassadors. A council made up of representatives from the five major space-faring civilizations - the Earth Alliance, Minbari Federation, Centauri Republic, Narn Regime, and Vorlon Empire - work with the League of Non-Aligned Worlds to keep interstellar relations under control. Aside from its diplomatic function, Babylon 5 also serves as a military post for Earth and a port of call for travelers, traders, businessmen, criminals, and Rangers.