Nelson Mandela Muntz Sr (born October 30, 1979) is a major character and recurring antagonist of The Simpsons and a child citizen of Springfield. He is the one of the school bullies at Springfield Elementary School. He is a fourth grader. Nelson was first shown as a bully and the arch-rival of Bart who took him to a fight. Over the years, he has terrorized most male kids in Springfield and was even seen bullying teenagers (also known as Jimbo Jones and the Squeaky-voiced Teen). Nelson has a manner of showing up in awkward situations of surprise or misfortune and regularly pinpoint it by laughing at the concerned people ('Ha-ha!' became his catchphrase). When cornered about the awkwardness of those situations, Nelson usually gives a very reasoned explanation as to why he acted the way he did, sometimes even pseudo-scientifically proving it ('See, epidermis means your hair, so technically it's true. That's what makes it so funny.') Nelson currently studies in the fourth grade but was already a student when Bart Simpson came to school. As he said on one occasion, 'I've been held back more times than I can count. Which I guess is why I keep getting held back.' As such, he mainly remains skeptical of Edna Krabappel's remarks and laughs at nerds present in his class as he well knows all the correct answers to the teacher's every question. (Source: Fandom.com, CC BY-SA)