Erik

The 5th Grader (real name not revealed) is a member of the 5th grade class at Springfield Elementary School. He used to be friends with Bart, the first and the second boy as children.

History
After Bart hits him to get him out in dodgeball, he caught the ball, which had been flung high into the air after hitting him, meaning that the fourth graders lost the game. This started a war in the school between the fourth and fifth graders. Eventually, when the fourth and fifth grades planned to commit a brawl after school, Bart realized that he and the 5th grader have the same sword-shaped scar on his hand.

Bart found out that Marge used to be a member of a group called The Cool Moms. They would take their children on play dates and the 5th grader was one of them. As Marge and the other moms got back together, so did their children. The 5th grader and the two other kids dared Bart to do crazy things and Bart wanted to split them up again, which they eventually did. The 5th grader has yet to reappear in future episodes.