The main villain in Terminator 3: Rise of the Machines is the T-X, a female Terminator designed to eliminate future resistance leaders and other advanced machines.
Kristanna Loken played the T-X, which combines an armored endoskeleton with a liquid-metal exterior. This design gives the character abilities associated with earlier Terminator models while adding weapons built into its body, including a plasma cannon and a flamethrower. The T-X is sent back to target John Connor and future resistance officer Kate Brewster.
The T-X is sometimes confused with the T-1000 from Terminator 2: Judgment Day because both can use liquid-metal transformations. They are different models, however, and appear in different films. Terminator 3 also introduces the idea that the T-X can control or infect other machines, making it a technological advancement within the series’ fictional chronology.