Amaterasu is a Stargate SG-1 System Lord who wasn't introduced until season 8. After Anubis' defeat, she laid claim to his base and Kull Warriors and used these resources to gain power.

"Stargate SG-1" was cancelled by the Sci-Fi channel. A 10-season run is impressive, though, especially considering "SG-1" was almost axed after season 8 to make way for another series. By season 8 ...