he first season of the television series Stargate Atlantis commenced airing on the Sci Fi Channel in the United States on July 16, 2004, concluded on The Movie Network in Canada on January 31, 2005, and contained 20 episodes. The show was a spin off of sister show, Stargate SG-1. Stargate Atlantis re-introduced supporting characters from the SG-1 universe, such as Elizabeth Weir and Rodney McKay among others. The show also included new characters such as Teyla Emmagan and John Sheppard. The first season is about a military-science expedition team discovering Atlantis and exploring the Pegasus Galaxy. However, there is no way to return home, and they inadvertently awake a hostile alien race known as the Wraith, whose primary goal is to gather a fleet to invade Atlantis and find their new "feeding ground", Earth.
The two-hour premiere "Rising", which aired on July 16, 2004, received Sci Fi Channel's highest-ever rating for a series premiere and episode ever released, it is also the most watched broadcast release ever released by the Sci Fi Channel in the United States. The average viewing rate for the first ten episodes were around 3-4 million in the United States. The series was developed by Brad Wright and Robert C. Cooper, who also served as executive producers. Season one regular cast members included Joe Flanigan, Torri Higginson, Rainbow Sun Francks, Rachel Luttrell, and David Hewlett.Overview from themoviedb.org