|Spoilers for The Bureau: XCOM Declassified follow.|
Shamash is an ancient possibly female Ethereal who communicates with a certain authority when speaking with the much younger Asaru. She is not arrogant, though, and is willing to listen to other points of view. She agrees that Origin must be stopped and is willing to commit double genocide for the "greater good" of the universe, and other species. As such, she has a broader perspective than Asaru. Shamash glows a bright orange as opposed to Asaru's blue; this may be due to her gender, older age or simply a different aura.
Shamash encountered Origin, a young Zudjari scientist, and merged with him to guide his species into a technological Golden Age. Origin, however, betrayed Shamash and used her to power Mosaic, a communication network that allows him to impose and bend others will to his, using her psionic powers, effectively mind controlling his entire species.
Shortly after she was rescued by Carter and put into the Elerium tank, she awakened and communicated with Asaru, another Ethereal merged with Carter. They spoke on how to effectively stop Origin: destroy both the Zudjari and Humanity. Asaru disagreed, and believed humans could be saved. Carter, realizing he was being mind controlled, shot Shamash with his pistol, killing her.
- It seems that two Ethereals meeting is relatively rare, as Shamash notes this to Asaru.
- According to her, they have lost or forgotten their homeworld.
- They seem to have a mission to better other species.