Season 5 Episode 19 - Menace

SG-1 explores a planet and finds an inactive android. When they reactivate it, it identifies itself as Reese and doesn't seem to know it's an android. Meanwhile, they find evidence that the Replicators were active on the planet. Reese doesn't accept she is an android and seems intent on getting out, while making "toys" using the nanotechnology in her own body, including a Replicator. When confronted Reese confesses she built the Replicators and they got out of her control and killed her "father" and everyone else on the planet, and when she gets out of control the Replicator goes berserk. Unable to contact the Asgard, Hammond orders SG-1 to shut down the Reese robot. She sends the Replicators through the base and heads for the Stargate, and Daniel goes in to try and win her trust and remove her power chip but fails. Hammond and Carter set the self-destruct while Jack gets in and shoots Reese - she shuts down the Replicators before she finally "dies".