The Replicators were artificial life forms that were built on nanotechnology. At first, they were created by an android named Reese as toys, but soon they became independent with the highest priority being survival through replication, hence their name. An attempt by the Asgard to stop their devouring of technologically advanced civilizations (they used the technology to create more of themselves) unintentionally led the Replicators to evolve from bug-like to humanoid. The Human Form Replicators held the intelligence capability of their creator, Reese. All Replicators, both bug-like and human form, were annihilated using the Weapon on Dakara. The Replicators were introduced in the episode 3.22 "Nemesis Part 1" and the Human Form Replicators, in the episode 6.12 "Unnatural Selection". All Replicators were destroyed in 8.17 "Reckoning Part 2".