Eliza

Eliza is a rival to Lisa.

History
She and her brother Lester manage to save Itchy and Scratchy Studios before Bart and Lisa do. Apu thanks them for helping him after he was arrested for public nudity and Krusty also thanks them for reuniting him with his estranged wife.

Later, an episode of Itchy and Scratchy is dedicated to them. Bart tells Marge that there is something unsettling about the fact that he and Lisa didn't solve the problem, before looking out the window and glaring at a skateboarding Lester.

Behind the Laughter
A girl who looks very similar to Eliza appears in Kamp Krusty in the grandstand just above Lisa, although since the character wasn't created at this point, it is likely a coincidence.

Trivia

 * Eliza has the same name as Lisa's ancestor, Eliza Simpson