Atlas was an Ancient scientist who lived during the time of the Lantean's reign within the Pegasus galaxy. He was the developer of the Exogenesis device and petitioned for the active use of the technology but was denied by the Ancient Council. Despite this, he took a contigent of fellow scientists along with his wife Ea and their son to test the device. Unfortunately, the expedition came under attack from the Wraith and resulted in the death of numerous scientists including his son.
Atlas along with Ea and the surviving scientists managed to flee in their transport which was also destroyed as they reached Lantea. He along with Ea managed to flee in a Puddle Jumper and attempted to reach Atlantis where they discovered that Moros and the rest of their kind had fled back to Earth. Abandoned, as the shield prevented their entry into the city, Atlas and the wounded Ea attempted to go into stasis and wait for the time when their kind would return for them.
Sadly, this was not to be as Atlas's stasis pod was damaged from the thousands of years buried under the ocean of Lantea and he was effectively killed when his pods memory module was destroyed when it was being recovered by the Atlantis expedition. (SGA: "Exogenesis")