Nirrti

"That woman continues to get on my nerves."

- Colonel Jack O'Neill

Nirrti was a Goa'uld System Lord who experimented to discover advanced humans.

1997
Nirrti seemed obsessed with creating enhanced humans (hok'tar) which could serve as hosts. She tried various experiments including killing the inhabitants of the planet Hanka with a bacterial infection. The only survivor being a young girl named Cassandra who she planted a bomb in to destroy Earth's Stargate. Fortunately, Cassandra lived and was adopted by Dr. Janet Fraiser.

1999
Later, when the System Lords agreed to negotiate with the Asgard to include Earth in the Protected Planets Treaty, Nirrti accompanied Cronus and Yu as part of the delegation. She felt that the Tau'ri were too much of a threat, and also coveted Cronus' domain. Using cloaking technology, Nirrti attacked Cronus in his quarters, framing Teal'c for the attack. Colonel Jack O'Neill decided to bluff, saying that they knew she was experimenting with phase shifting technology, and she exposed herself. She was captured and became a prisoner of Cronus.

2001
After Cronus was killed by SG-1, Nirrti managed to rebuild her resources while the rest of the System Lords were distracted by the return of Anubis. She found out that Cassandra Fraiser was still alive and attempted to find more information about Cassandra in order to conduct more experiments on other people. At one point, she managed to sneak into Stargate Command using a Goa'uld cloaking device that made her invisible. When she was eventually discovered and captured, she offered to help save Cassandra, who was dying of a retrovirus that was turning her into a hok'tar. Nirrti demand her freedom, cloaking device, and a sample of Cassandra's blood in exchange. Major General George S. Hammond initially refused. In an act of desperation, Dr. Janet Fraiser held Nirrti at gun point, demanding that she help. After Hammond agreed to free her, and reminded her that Fraiser was Cassandra's adopted mother, Nirrti healed the girl, and was allowed to leave unharmed.

2003
The Russian SG-4 team later discovered her experiments to create a hok'tar on the planet P3X-367, this time through genetic manipulation, finding Alebran in his ruined city after he had left Nirrti. They brought him back to Stargate Command to speak to SG-1, as it was because of them that Nirrti was still free. Alebran informed them of all that he knew but soon died due to Nirrti's experiments, seeming to turn into liquid. The two SG teams returned to the planet in order to help the natives, but the natives did not believe that Nirrti was evil as she had been the one to save them from a plague which had ravished their planet. Teal'c and Jonas Quinn were taken prisoner by the natives after Eggar discovered their intent to kill Nirrti in O'Neill's mind, and the others were soon captured upon Nirrti's return also.

SG-1 attempted to inform the native's of Nirrti's true motives while Nirrti performed experiments on both teams, meeting with no success for some time. Nirrti performed several experiments on members of both teams before finding that Jonas's Kelownan heritage had caused him to be somewhat more evolved than the Tau'ri. She was sure she could create her hok'tar in him, and even asked if he would submit to allow her to do so. Although Jonas rejected the offer, Nirrti none-the-less performed several experiments on him. During this time, however, SG-1 was able to somewhat convince the natives of Nirrti's true intents and after Eggar read her mind he discovered this to be true. Wodan then killed Nirrti by telekinetically breaking her neck, but not before she made subtle modifications to Jonas's DNA that resulted in him developing the ability to see into multiple futures during a later mission. Also, Eggar read her mind before her death, allowing him to reverse what she'd done to everyone.

Novel
Nirrti plays a prominent role in the novel Stargate SG-1: Survival of the Fittest, where Adrian Conrad's Goa'uld is able to help Colonel Frank Simmons make a deal with Nirrti, allowing her to capture Janet Frasier as part of her revenge for defying her attempts to analyse Cassandra in exchange for the knowledge of how to genetically engineer humans into Jaffa. Her plan is thwarted when SG-1 manage to rescue Frasier, with General Hammond and Bra'tac leading the effort to kill the 'new' Jaffa that she had created.

Alternate timeline

 * In an alternate timeline created by Ba'al, he conquered several System Lords, including Nirrti, who served under him and participated in an attack on Earth. She, along with Qetesh, believed that the Tau'ri "should be blasted to the brink of extinction" finding such an idea "enjoyable".