Sartana Rivera is a character played by Jessica Alba in the movie "Machete." Sartana is a U.S. immigration agent who is tasked with bringing down the vigilante Machete (played by Danny Trejo) after he is accused of committing a series of violent crimes. Throughout the course of the film, Sartana is a major adversary to Machete, as she tries to track him down and bring him to justice. However, as the film progresses, she begins to see the truth about the situation and realizes that Machete is not the villain he has been made out to be.

In the film, Sartana is depicted as a tough and determined law enforcement officer, who is committed to her job and to bringing criminals to justice. She is also depicted as a conflicted character, as she begins to question the motives and methods of the government she works for, and starts to see the human side of Machete. Jessica Alba's performance as Sartana is widely regarded as one of the highlights of the film, and she brings a sense of depth and nuance to the character that is both surprising and engaging.

Overall, Sartana Rivera is an important and memorable character in "Machete," and is a testament to Jessica Alba's versatility and range as an actress. Whether she's playing a law enforcement officer or a villain, Alba is always able to bring a unique and captivating energy to her roles, and her performance as Sartana is no exception.