Stargate canon

The SG-1/Atlantis/Universe canon refers to the Stargate universe depicted in Stargate SG-1, Stargate Atlantis and Stargate Universe 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 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/Universe 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. In disputes between evidence seen on screen and information from other sources (even official ones, such as the MGM Tech Journal), the evidence on screen will always take precedence.

Internal contradictions
There are some elements of the series that are considered to be inconsistencies 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/Universe canon. However these kinds of mistakes are generally considered excusable and understandable as they mostly serve to lower production costs.

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 four distinct timelines in which major portions of the series take place: one from Stargate to the beginning of Moebius, Part 1, a second from Moebius to The Last Man, third from The Last Man to Time, and two within Time, with the fifth from Time to present. The focus of this wiki is the post-Time timeline, as it's the setting of the ongoing series as of 2009; however, articles generally assume that this timeline is identical to the previous four, except where explicitly shown otherwise.

Similarly, Stargate: Continuum features a time-travel story that creates yet another 2 timelines, which brings the grand total of timelines to eight.

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/Universe 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 in Stargate and Stargate SG-1,

Differences between the SG-1/Atlantis/Universe and the Infinity universe

 * The unstable vortex does not annihilate whatever it comes into contact with.
 * The Ancients are winged, telepathic creatures.
 * The Stargates only have eight chevrons.