Dead Bart is a famous creepypasta based around a fictional distributing lost episode of the American long-running sitcom TV series The Simpsons. It is one of the, "Lost Episode" creepypastas.
The episode itself is about a lost episode received on a hard drive about The Simpsons family going on a vacation, and then suddenly Bart breaks a window inside the plane and gets thrown out and falls out of the plane and onto the tarmac where he dies, and it shows his corpse in a hyper realistic way. (A popular phenomenon in "Lost Episode" creepypastas.) Then the family mourning his death in the kitchen after coming back from the vacation with hidden faces in the windows flashing for nanoseconds, and then them going to a cemetery and seeing his dead body on the grave, as well as cast member's tombstones being shown in the cemetery that eventually would later die in the series later on. (Hinting to the fact that The Simpsons always perfectly predicts the future, which is their trademark.)