Stargate Atlantis (often abbreviated as SGA) is an American-Canadian science fiction television program, part of the Stargate franchise owned by MGM. Developed by producers Brad Wright and Robert C. Cooper, it is a spin-off from the television series Stargate SG-1. It is filmed and produced in Canada.
Stargate Atlantis follows the adventures of a human expedition to the lost city of Atlantis in the Pegasus Galaxy. The Stargate has brought humanity into contact with other cultures, including new and powerful enemies: the Wraith, the Genii, and later the Asurans, all while trying to uncover the secrets the Ancients left behind.
Stargate Atlantis premiered on the US Sci Fi Channel on July 16, 2004 with "Rising", a movie-style two-part episode, that guest starred Richard Dean Anderson and Michael Shanks from Stargate SG-1. The series is broadcast in HD in selected countries including the US, which is shown sometimes on Universal HD and as of 2007 is now simulcast in HD on Sci Fi.