Jeff Kleiser and a special effects team working on Stargate (1994) the film, used around 40 people and used self-written image-creation and composition software, as well as commercial digital packages to create the Stargate, the morphing helmets worn by Ra and the Horus guards. The pharaoh mask in the opening credits was made out of fiber glass and was modeled in the workshop. The sequence was filmed with a motion-control camera to give a better depth of field. The film was originally planned to play out in a chronological order, but when Dean Devlin and Roland Emmerich edited the film to tighten the narrative, they decided to change the first scene of the film into a flashback to show who the human host of Ra was before the aliens took him. The Jaffa (from Stargate SG-1) look in the series was copied from the Egyptian look of Ra from the film. The look of the Goa'uld, such as Apophis, was initially based on Ra in the feature film.
Since the eighth season of Stargate SG-1 was intended to be the last, the producers had finished it with the defeat of the Goa'uld and the Replicators. However, when the Sci Fi Channel renewed the series, the producers had grown tired of writing endings. Having had good experiences with the first season of Stargate Atlantis, the producers decided to revamp the series by more than just adding new characters, new villains and new missions. Thus they considered the beginning of Season 9 as the pilot of a new show and replaced the Goa'uld with the Ori as the main villains. The Goa'uld still appeared in the show, but on a regular basis under the command of Ba'al.
The astronomers David J. Tholen and Roy A. Tucker enjoyed the SG-1 arch villain Apophis so much that they named their discovered near-Earth asteroid "99942 Apophis".
In the Stargate universe, the word "Goa'uld" means "god". The Goa'uld evolved on the planet P3X-888, where there are still populations of primitive Goa'uld. Their original hosts were the Unas, also native to the planet. The Goa'uld largely abandoned P3X-888 after deciphering the Stargate, spreading throughout the galaxy and conquering other races. Eventually, the Goa'uld began to die out, until in the eighth or ninth millennium BC Ra discovered Earth and found ancient humans to be much more suitable hosts, due to the ease by which they can be repaired by Goa'uld technology.
The Goa'uld ruled Earth for thousands of years, in the personae of gods from Earth's classical religions. It is never clarified, however, whether the Goa'uld impersonate deities that already existed in human mythology or if they themselves were the origin of those deities. From the humans, the Goa'uld engineered the Jaffa, who serve as soldiers and incubators for their young. They also transplanted significant numbers of humans from Earth throughout the galaxy via the Stargate network to serve as slaves and potential hosts. After Ra's rule over Earth came to an end with a rebellion in the third millennium BC, after which the Stargate was buried in the ground to render it unusable, Earth was largely forgotten and for some reason never revisited; this is possibly because Earth contained no notable natural resources such as naqahdah, and the Goa'uld had already established sustainable human slave populations of sufficient size for genetic diversity elsewhere, obviating the need to return to our inconveniently distant planet. Earth passed into legend amongst the human and Jaffa populations of the galaxy, until the 20th century, when the Stargate was discovered and eventually activated.
In the continuity of Stargate SG-1, the first Goa'uld faced by Earth is Ra in the Stargate film, although the concept of the Goa'uld had not yet been developed when the movie was released. In the early seasons of the show, SG-1 faces and defeats the powerful Goa'uld Apophis twice, as well as Hathor and Sokar, and gains an alliance with the Tok'ra. The System Lords begin to play a larger role in the show as SG-1's activities draw their attention to Earth, and SG-1 defeats several of their number as well. In season 5, the half-Ascended Goa'uld Anubis becomes the main threat, eventually leading SG-1 on a race to discover Ancient technology capable of defeating him. Anubis is seemingly destroyed at the end of season 7, and Ba'al takes his place as the major villain in season 8. The Goa'uld also establish a foothold on Earth by infiltrating the Trust. Near the end of season 8, SG-1, the Tok'ra, and the Jaffa rebellion finally overthrow the Goa'uld order, and Anubis is defeated once and for all. The Goa'uld have a diminished role in seasons 9 and 10, with Ba'al being the only remaining major Goa'uld character and representing a third major side in the fight between SG-1 and the Ori until he is finally shot and killed by Cameron Mitchell.
Goa'uld symbiotes are serpentine lifeforms with four jaws and glowing yellow eyes. Originally aquatic, mature Goa'uld symbiotes have extensive fins and are powerful swimmers, with the ability to launch themselves from the water towards prospective hosts. A Goa'uld can burrow into their host through the back of the mouth or the neck, though they prefer the latter because they wish to avoid remembering the look of horror on the host's face. They then enter the brain, take control of the body, and gain total access to the host's memories; thus, the Goa'uld often use symbiote implantation as a means of interrogation that also provides a useful future spy.
A defining characteristic of a Goa'uld host is a brief glowing of the eyes. This occurs when the Goa'uld first takes control and upon its death, as well as in moments of extreme emotion or to add emphasis or intimidation. A Goa'uld-occupied host typically speaks in an eerily flanged, deepened register. However, the voice is not necessary, and Goa'uld can speak in a normal tone if they choose, usually when they need to deceive someone. The Goa'uld instill their hosts with superhuman strength, perfect health, and accelerated healing. The host's life is also lengthened into centuries, which the Goa'uld extend even further using a sarcophagus. However, repeated use of the sarcophagus has severe psychological consequences, and is believed to be a main factor in the Goa'uld's evil. Being host to a Goa'uld has been described as a living nightmare, and those humans who have been hosts for thousands of years are widely suspected to have gone insane.
Once implanted, the Goa'uld loses its fins and its body atrophies, leaving only a dead husk behind, as seen with Charles Kawalsky. Modern Goa'uld symbiotes contain the fictional element naqahdah in their bloodstream, an attribute that is passed on to their host. The naqahdah allows Goa'uld, Jaffa, and former Goa'uld hosts to sense the presence of other symbiotes. However, the primordial Goa'uld on P3X-888 do not possess naqahdah. Implanted symbiotes cannot be removed from their host via conventional surgery; it can retain control of the host even if the symbiote's original body is cut away. The symbiote can also release a deadly toxin into the host if it is threatened, and holding the life of the host hostage is a common Goa'uld tactic. The Tok'ra have developed a means to extract the symbiote while sparing the host and resulting in the death of the symbiote. It has been shown that the Tollan have a means to remove the symbiote allowing both the symbiote and host to live. The Asgard have also developed their own means of separating a Goa'uld symbiote from its host. If an implanted symbiote dies without releasing the toxin, its body is absorbed into the body of the host.
The Goa'uld possess a genetic memory passed directly from parent to offspring, which perpetuates the evil of the Goa'uld through generations. Most Goa'uld are asexual, though they usually take on the gender of their preferred host. The exception are the Goa'uld Queens, who over time are able to spawn millions of larvae, once seeded with genetic material from another Goa'uld or even a human. Queens exercise a great deal of control over the biochemistry of their progeny, and can deny their offspring genetic memory in order to create "blank" symbiotes. Goa'uld larvae that mature in the wild have only a 50% chance of successfully taking a host; the Goa'uld engineered the Jaffa as incubators to improve these odds. The human offspring of two Goa'uld hosts is known as a Harcesis. The conception of Harcesis children is forbidden, as they would contain the genetic memories of both Goa'uld parents and thus pose a major threat to the established Goa'uld order.
In the Stargate film, Daniel Jackson identifies the language spoken by Ra and the Abydonians as a variant of ancient Egyptian. The fictional language of the Goa'uld on Stargate SG-1 is also spoken by their human slaves and the Jaffa, often interchanging with English dialogue without explanation. The most commonly used Goa'uld words in the show are "chappa'ai" ("Stargate"), "Tau'ri" (both "Earth" and "Earthlings", can also be translated as "those who came before", referencing the galaxy's human population's planet of origin), "shol'va" ("traitor", frequently applied to Teal'c by various Goa'uld and Jaffa characters), and "Kree" (with many possible meanings including "come", "listen up", "go", "attention", "be prepared" and "take aim"; appearing in many different episodes under different contexts). Most Goa'uld written script used in the show are based on the Egyptian hieroglyphic script. The alphabet in the series is actually the Nakht hieroglyphic font, and it was used to write various jokes in different episodes. Another hieroglyph font used in the series was the Meroitic script.
The Goa'uld scavenged or conquered most of their advanced technologies from other races. However, there are innovators amongst the Goa'uld; Anubis and Ba'al in particular have been depicted with a great deal of technological ingenuity. Many Goa'uld devices, such as the staff weapon, are designed to be more showy than practical, meant to intimidate and reinforce their position as gods to their followers. Some pieces of Goa'uld technology, such as the hand device and the healing device, respond only to mental commands and require naqahdah in the bloodstream of the user to operate.
At the time that Stargate SG-1 begins, the Goa'uld are presented as the dominant species of the Milky Way galaxy, having been so for millennia. By and large, the Goa'uld are shown to be utterly arrogant and obsessed with gaining personal power. To this end, they constantly scheme and fight amongst themselves. Arrogance is presented as their greatest weakness; Teal'c once states that he has seen many brilliant battle plans fall apart because a single Goa'uld needed to boast about them. The Goa'uld are shown to rule by fear and oppression, regularly employing mass torture and execution, and using their advanced technology to present themselves as omnipotent gods. They are presented as regularly attacking advanced races that they believe may pose a potential threat, such as the Reetou and the Re'ol, while suppressing technological progress in their own subject populations.
The more powerful Goa'uld are presented as controlling multiple planets, armies of Jaffa warriors, and fleets of motherships. They live in luxury, attended by scores of loyal slaves. When one Goa'uld defeats another in battle, the vanquished enemy's domain and forces are typically absorbed by the victor. Sometimes, Goa'uld will ally with each other to pursue a greater objective; usually these alliances dissolve in treachery as soon as one party senses an advantage.
The System Lords are the collective of the most powerful Goa'uld in the galaxy. In the episode "New Order", Daniel Jackson describes them as "posturing egomaniacs driven by an insatiable lust for power, each one capable of unimaginable evil". There are around a dozen System Lords at any one time; their ranks change frequently as new ones rise and old ones fall, but a number of them have managed to maintain their position for hundreds or even thousands of years. In order to become a System Lord, a Goa'uld must be acknowledged in that role by a majority of the currently sitting System Lords. The System Lords control vast territories and armies; in "Fair Game," they are stated to be capable of launching an attack against Earth 100 times the strength of that sent by Apophis at the end of season 1. For thousands of years until his defeat by Jack O'Neill and Daniel Jackson, Ra held the position of Supreme System Lord.
The System Lords are not a unified body and frequently war against each other for dominance, though they will ally in the face of mutual threats. One of the main strategies of both the Tok'ra and the Asgard is to play the System Lords against one another, so that no single one of them becomes too powerful to topple. The System Lords employ elite, highly dangerous Goa'uld assassins known as Ash'raks, who have been known to use stealth devices to become invisible, and wield a device called a hara'kesh that serves as a weapon, an interrogation device, and an instrument of torture. The System Lords can also turn captured enemies into assassins called za'tarcs, using mind control to implant dormant commands hidden by false memories. People who are turned into za'tarcs are not aware of it until their programming activates. A System Lord's most trusted servant and confidant is called a lo'taur, a human slave who can be used as a host in an emergency. Some of these loyal humans serve willingly for the chance of one day experiencing the "pleasures" of being a Goa'uld host.
The first System Lord seen on Stargate SG-1 is Apophis, although the show retroactively established Ra from the Stargate film as a System Lord. In "Fair Game", the three System Lords that come to Earth are Cronus, Nirrti, and Yu. In "Summit" and "Last Stand", a meeting of the System Lords is shown, featuring Yu, Ba'al, Bastet, Kali, Olokun, Morrigan, and Svarog. In those episodes, Anubis is also accepted back into the ranks of the System Lords. The episode "New Order" introduces two new System Lords, Amaterasu and Camulus. Two unknown System Lords are shown alongside Yu in "Reckoning". Other Goa'uld mentioned to be System Lords at one point or another are Sokar, Hathor, Heru-ur, Seth and Ares. The most powerful Goa'uld eventually to come to power is Anubis, but he is eventually defeated by an Ancient weapon system in Antarctica, and later is removed from the temporal plane by Oma Desala.
One of the most prominent elements of Goa'uld society is their tendency to pose as gods to other, weaker races, mostly humans and Jaffa. Goa'uld are shown to do this because of the luxury and power it brings, and to have their followers mine naqahdah. They fool minor races into believing that they are gods by passing off their technology as magic. Examples of this include opening the Stargate, using hand devices, and their metallic masks, which give them an other-worldly appearance. Some Goa'uld, such as Ba'al and Yu, rule more through cunning than through the facade of divinity, although this is unusual.
Masks are first seen in the original movie. They often are covered in decorative frills, and have glowing eye-beads. They are designed for show rather than functionality. Four versions of these have been seen: Pharaoh Mask (worn by Ra), Horus Mask (Ra's Horus Jaffa and Heru-ur's Jaffa), Jackal mask (Leader of Ra's Jaffa, originally Anubis), and Serpent Mask (Apophis and his Jaffa). Seth Masks (worn by Seth and his Jaffa) have been mentioned, though never shown.
The Tok'ra (literally meaning "against Ra") are a benevolent offshoot of the Goa'uld, who oppose them philosophically and militarily. Spawned from the Goa'uld queen Egeria, they only blend or join willing hosts, with whom they share the body equally and enjoy a truly symbiotic relationship. In Stargate SG-1, the Tok'ra become valuable allies of Earth and play a critical role in the eventual defeat of the Goa'uld.