Season eight of Stargate SG-1, an American-Canadian military science fiction television series, began airing on July 9, 2004 on the Sci Fi channel. The eighth season concluded on February 22, 2005, after 20 episodes on British Sky One, which overtook the Sci Fi Channel in mid-season. This was the first season of the show to have 20 episodes instead of 22, as well as the first to air concurrently with Stargate SG-1 spinoff series Stargate Atlantis. The series was originally developed by Brad Wright and Jonathan Glassner, while Brad Wright and Robert C. Cooper served as executive producers. Season eight regular cast members include Richard Dean Anderson, Amanda Tapping, Christopher Judge, and Michael Shanks. The eighth season begins with the SG-1 team trying to revive Colonel Jack O'Neill after the events of the seventh season. At the end of the two-episode season opener, Colonel O'Neill is promoted to General and assumes command of Stargate Command, while Major Samantha Carter is promoted to Lieutenant Colonel and assumes command of SG-1. The season arc centers around the growing threat and seemingly final defeat of the Goa'uld and the Replicators, races who were introduced in the first and third season of the show, respectively.