"They Saved Lisa's Brain" is the twenty-second and penultimate episode of the tenth season of the American animated television series The Simpsons. It first aired on the Fox network in the United States on May 9, 1999. In the episode, after writing a thoughtful letter to the Springfield Shopper, Lisa is invited to join the Springfield chapter of Mensa. When Mayor Quimby later flees Springfield, the group takes control of the town, hoping to improve the lives of Springfieldians through the rule of the smartest. Meanwhile, Homer poses for a series of erotic photos.

The tenth season of the American animated television series The Simpsons was originally broadcast on the Fox network in the United States between August 23, 1998, and May 16, 1999. It contains twenty-three episodes, starting with "Lard of the Dance". The Simpsons is a satire of a middle-class American lifestyle epitomized by its family of the same name, which consists of Homer, Marge, Bart, Lisa and Maggie. Set in the fictional city of Springfield, the show lampoons American culture, society, television, and many aspects of the human condition.