Ludwig is the main antagonist in Hey Arnold! episode New Bully on the Block. He is a bully who is Wolfgang's rival turn friend.
Ludwig was in juvenile hall and he tries to reclaim his vacant lot (which is used to be his before the fourth grade students claimed it). He takes some of the kid's lunch money while Arnold tells him that Wolfgang surrenders. Arnold has Ludwig and Wolfgang plays a game of football to see who gets the vacant lot and the bullies uses the 4th grade students to play with. The game is a tied and they both agree to share the vacant lot and still pick on the 4th graders. Ludwig and Wolfgang puches all the 4th grade students and hangs then by thier shirts while Ludwig and Wolfgang congratulate each other and become friends.