Wikipedia
The Goa'uld (pronounced ; commonly shortened to or ) are a symbiotic race of ancient astronauts from the American-Canadian military science fiction television franchise Stargate. The Goa'uld are parasites from the planet P3X-888, integrated within a host, most of the time a human. The resulting creatures are a powerful race bent on galactic conquest and domination, largely without pity, compassion or remorse. In the first eight seasons of Stargate SG-1, they are the greatest extraterrestrial threat to Earth known to the Stargate Command (SGC). The Goa'uld are the main enemies of SG-1 for most of the show, until they are replaced in this capacity by the Ori in seasons 9 and 10. They also appear in the Stargate Atlantis episode , and in the DVD movie Stargate: Continuum. They are pejoratively called "snakes" or "snakeheads" by Jack O'Neill.
The Goa'uld were created by writers Dean Devlin and Roland Emmerich for the 1994 movie, Stargate. Although the alien race in the film was never named, the pilot episode " Children of the Gods" (1997) established that the alien race seen in the movie are the Goa'uld. In the series, it is confirmed that they are a parasitic race that uses hosts to survive. They were the dominant species in our galaxy.