Goa'uld arc

The pilot episode ("Children of the Gods"), set one year after the events of the original feature film, introduces the Goa'uld System Lordand main villain Apophis (Peter Williams) as he attacks Earth's mothballed SGC military base through the Stargate and kidnaps a soldier. The SGC is brought back into action when the Stargate is revealed to be part of an interplanetary network connecting countless planets. SG teams are created to help defend Earth against the Goa'uld, who have interstellar pyramid warships and vast armies of Jaffa(hereditary slaves and human incubators to the Goa'uld) at their disposal. Earth's flagship team SG-1, which includes Apophis's defected First Prime (lead Jaffa soldier) Teal'c, initiates several alliances with other cultures in the galaxy, such as the Goa'uld-like but truly symbioticTok'ra, the advanced human Tollan, the pacifist Nox, the benevolent Roswell-alien Asgard, and remnants of the powerful Ancients. Another alien threat arises in the season 3 finale ("Nemesis") in the form of sentient machines called Replicators. Meanwhile, rogue agents of a shadowy intelligence agency on Earth, the NID, repeatedly attempt to take control of the Stargate and other alien technology. Despite Apophis's death in the beginning of season 5, the Goa'uld Empire remains a major foe in Stargate SG-1 until the end of season 8. The only influential Goa'uld in the last two seasons of Stargate SG-1 is the System Lord Ba'al (Cliff Simon), who is defeated in the direct-to-DVD filmStargate: Continuum.