Stargate: Every Villain Ranked Worst To Best

About halfway through the run of Stargate Atlantis, we are introduced to a highly advanced civilisation of Ancients in the Pegasus Galaxy that have apparently been twiddling their thumbs for the last ten thousand years, since the Wraith took over the Galaxy. When the Atlantis expedition encounters them, they are at first thrilled to have found someone who might be able to help them out properly. Alas, all is not as it seems.

These aren't Ancients, these are Replicators. Since there was already a mechanical race of beings called Replicators (the relationship between which has never been properly established), these beings are referred to as Asuran Replicators or just Asurans. They are built from nanobot cells that can form up into human shapes, in order to ape their creators.

While these Replicators had been rebuilding for the last ten thousand years, the encounter with the Atlantis Expedition provoked them into conflict and their ability to infest people with nanobots was certainly sinister. The climax of Atlantis season 3 sees the city come under attack from an ingenious assault from the Asurans that would take great sacrifice and cunning to overcome.

Eventually, the Asurans would meet their end when Atlantis brought together an alliance of Tau'ri, Traveller and even Wraith ships to fight them.