Stargate canon

The SG-1/Atlantis canon refers to the Stargate universe depicted in Stargate SG-1 and Stargate Atlantis and the universe that this wiki is dedicated to. This universe is based on the one depicted in the Stargate film, but there are some differences. However, it is clear that the events depicted in the film did occur in the SG-1/Atlantis universe and elements of the film are considered canon so long as they aren't directly contradicted by the series.

There are many novels, comics, role playing games and other works set in this universe, meaning they use the characters and elements of the Stargate universe as seen in the SG-1/Atlantis canon to create storylines. Though the role-playing books have been classified as canon, neither the novels nor the comics have had an official word said either way and so it is unclear whether or not they are canon.

Internal contradictions
There are some elements of the series that are considered to be inconsistences and therefore not exactly canon. For example, in the scene from the SG-1 episode "Solitudes" where P4A-771 is being dialed from the SGC, archive footage of the dialing computer was reused, so the gate address depicted is actually that of Abydos. Since it would be impossible for Abydos and P4A-771 to have the same gate address, the address portrayed in the episode must be inaccurate, despite the fact "Solitudes" is part of the official SG-1/Atlantis canon.

Another issue is that there are some characters who have been portrayed by more than one actor. A notable example would be Elizabeth Weir who was played by Jessica Steen in "Lost City, Parts 1" and "2," but by Torri Higginson for the remainder of the series. Steen and Higginson do have a somewhat similar appearance, but they could hardly be the same person. Since Higginson portrays the character in every episode of Stargate Atlantis and in all her other appearances in Stargate SG-1, her version of the character is considered more canon than Steen's version.

Time travel

 * Main article: Alternate reality

On more than one occasion, the SG-1 ' s narrative has followed characters jumping backwards in time, effectively creating a new timeline in which history has been changed by their presence. Thus, there are technically three distinct timelines in which major portions of the series take place: one from Stargate to the beginning of 1969, another from 1969 to Moebius, Part 1, and a third from Moebius to the present. The focus of this wiki is the post-Moebius timeline, as it's the setting of the ongoing series as of 2008; however, articles generally assume that this timeline is identical to the two previous ones, except where explicitly shown otherwise.

Similarly, Stargate: Continuum features a time-travel story that creates yet another timeline.

Alternate timelines created through time travel are distinct from the alternate realities accessible through a quantum mirror or similar technology, which exist simultaneously with one another in the same timeline.

Stargate, the movie canon
This is the universe depicted in the 1994 science-fiction film Stargate. Bill McCay's Stargate novels are set in this universe, but, as in the SG-1/Atlantis canon, novels are not considered canon, so the original Stargate film remains the only legitimate work set in this universe.

The physical appearances of many characters, notably Jack O'Neill, Catherine Langford and Louis Ferretti, are radically different in this universe, due to them being played by different actors. Other differences are listed below:

Infinity universe
This is the universe depicted in Stargate Infinity, which is based on the universes depicted Stargate and Stargate SG-1, but, once again, there are differences.

Differences with the SG-1/Atlantis universe

 * The unstable vortex does not dissolve whatever it hits.
 * The Ancients are winged, telepathic creatures