Bart Simpson- died temporarily in "Bart Gets Hit by a Car" when Mr. Burns hit him as the former was skateboarding. He came back to life a little bit later in the episode, he isn't technically considered a death.

How did Lisa Simpson die?

In "Flanders' Ladder", Lisa dies at age 98 from natural causes after realizing that she wasted her entire life.

What is Bart Simpsons IQ?

Dr. Pryor walks in on the meeting, and surprises everyone when he tells them that Bart is a “gifted child,” and according to the aptitude test from earlier, Bart has an I.Q. of 216. Dr.