Most sophontic species in the Traveller universe ported over to the Traveller:SGC universe with little modification. So, IMTU...
• Aslan: A Gua'uld host species. Never fully conquered, but willingly subjugated with promises of loot and land. Clashed fiercely with Jaffa.
• Droyne: A regressed ancient species. Biologically unsuitable as Gua'uld hosts. Replaced the Nox IMTU while retaining their psionic abilities.
• Humaniti: Played straight and as-is. People from Earth/Terra were called the Tau'ri. The Vilani made up the humans of other worlds. The Zhodani as a people were able to (just barely) avoid and repulse the Gua'uld. When an individual Zho was captured and taken over, he or she lost all natural psionic abilities, but was able to use mind-based Gua'uld devices to full effectiveness.
• Hiver: Physiologically unsuitable as Gua'uld hosts - their bodies would eventually reject and kill the Gua'uld larva as a parasite. Amoral manipulators of nearly every other sophontic species. Barely tolerated by the Tau'ri.
• K'kree: Legendary creatures, rumored to be infinitely wise and exceptionally fierce in battle. Never encountered IMTU, although they could have been, if only the Travellers had made a stopover at Al-Beqwar-K.
• Vargr: A Gua'uld host species. Willingly subjugated by the Gua'uld, whom they worshipped as gods. Fought alongside the Jaffa.
Ancient Species
• Altaran Ancients: Ancestors of Humaniti. Mostly canonical with the Stargate series'. Ascendancy was never established as anything but a rumor - one of many relating to the disappearance of the Altaran Ancients. Altaran DNA and Humaniti DNA are nearly identical. It was the Altarans that were the Ancients of the "Humaniti Hypothesis".
• Grandfather: The Droyne ancestor was an uplift - an experiment of the Altaran Ancients, just before they retreated back to the Pegasus galaxy. From that moment on, his history reverted to CT canon, with the inclusion of the Thousand Years War of the Droyne ancients. Every Droyne world has myths foretelling his return "someday".
Other Alien Species
• Asgard: Keepers of Ancient Knowledge. They are a dying species, having lost their ability to reproduce "in the usual way" - they must resort to cloning and mind transferrance (e.g., transmigration). Theirs is a race against time to find new Keepers, with the Tau'ri being the most promising species so far.
• Furlings: Mystery species. No one knows what happened to them. Their archeologic record abruptly stops sometime around the end of the Thousand Years War.
• Tok'ra: I played these people as even more aloof and uncooperative than in the series. While individually helpful (maybe), their society had a strict code of non-interference with "lesser" species.
• Other Species: The general rule was that minor species (those that had not achieved star travel on their own) were either primitive peoples (TL-4 or less) being exploited for their land and labor, or advanced peoples (TL-C or greater) capable of holding off exploitation. Species of moderate technological advancement (TL-5 to TL-B) were either at war with the Gua'uld, under the protection of a more advanced species, off the stargate network (i.e., no known stargate, buried stargate, iris barrier, et cetera), or experts at concealment.
There were exceptions to each rule, of course. The one that was most fun to play was when a clone of Ba'al appeared with a pet Hiver on a chain ... one a master strategist, and the other a master manipulator ... which one was really in charge ... ?
