Aegis was a Asgard spaceship used by Fenrir.

The Asgard Fenrir was convicted by the Asgard High Council to be put in stasis on his ship, the Aegis, on account of having made ​unauthorized tests of an Isa device in a populated star system. He was sentenced to be sent to roam the galactic cluster for five hundred seasons, on a course to get him back to the planet Hala when his punishment was over. His ship got into the Pegasus galaxy, and in a stroke of bad luck, he found himself among the planet Heruun and Wraith fleet who was preparing to culling its inhabitants when his ship dropped out of hyperspace a to make a course correction. Fenrir and his vastly superior ship managed to win the battle that followed, but took in injuries and crash-landed on Heruun's moon.

Stranded, with no way to completely repair his ship without help, he kidnapped several Heruun locals and temporarily brainwashed them to fix their ship for a period of weeks, then send them back home with their memories of where they were and made ​​at the time period erased. Aegis was eventually discovered by the Atlantis expedition who aided Fenrir in repairing the ship. However, Aegis was also discovered by the Wraith led by a Hive queen who sought to use the ship and its technology to destroy the Asurans and gain control over the Wraith. Fenrir was killed when the queen sacrificed herself to detonate a bomb in the command center, but he gave control of the ship to Colonel Samantha Carter. With the aid of Teyla Emmagan, Carter piloted the ship into battle against a hive ship, but due to unrepaired damage, the Aegis was no match for the hive ship and suffered heavy damage. At the same time, Wraith on board used the Aegis's matter conversion technology to create an Isa device. With no other choice, Carter rammed the hive ship with the Aegis and worked with Doctor Rodney McKay to use the Aegis Asgard hyperdrive to send the two ships into the interstellar void between stars. After great struggle, as the two ships started to fall into Heruun's atmosphere, the two were able to engage the Aegis hyperdrive while being beamed aboard one of the Asgard ship's auxiliary ships. The hyperspace jump took the Aegis and the hive ship hundreds of light years from Heruun where the isa device aged both ships to dust. (SGA: "Nightfall")

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