Dr. David Nelson is a man with dwarfism who comes to the South Park Elementary to give a talk about his experience in the Season Eleven episode, "With Apologies to Jesse Jackson". He was voiced by Trey Parker by taking in helium to create the distinct high pitched voice.
Nelson's only appearance is the episode "With Apologies to Jesse Jackson", in which he first appears to give a talk at South Park Elementary to all students. Upon entering, he is almost immediately laughed at and mocked by Cartman, which Nelson dismisses believing he'll stop eventually. Later, he complains to Principal Victoria and Mr. Mackey and claims that if he could have a one-on-one talk with Cartman, he could change his views, but as Cartman is sent in, he begins to laugh again, causing Dr. Nelson to have an outburst, yelling "Shut your fucking mouth!", to the shock of Principal Victoria. He is clearly embarrassed by this, claiming it was a joke, and that Cartman failed to break him.
Next, he gets all the fourth-graders to say "Hello, fatso!" when Cartman enters the room, which they do. Upon questioning who organized this, Nelson reveals himself, only to cause Cartman to laugh at him even more. Finally, they have a fight, in which Cartman gains the upper hand of making Nelson repeat a line said by a short person in the film Poltergeist. Cartman goes off guard for a few seconds, only for Nelson to kick him to the ground, and he then leaves, believing he's proven his point, with Cartman lying on the ground, once again laughing hysterically at Nelson.
Dr. Nelson seems to be a very intellectual man, having published six books in total, but after being pushed too far, in terms of mocking his dwarfism, he acts childish with constant attempts to get back, using juvenile - and later - violent methods. He does seem to have little concern over his condition if he is not teased about it too much, and constantly claims that he feels "Words are like bullets, and I let them pass straight through me."
Mentioned by Kyle to Eric, Nelson has a black belt in karate, which seems to show he is strong as well, but during his fight with Cartman, this does not seem the case, as Cartman nearly wins the fight, up until Nelson manages to finally floor Cartman with a single kick, before walking away, as Cartman continues to laugh at him for his dwarfism.
- His facial appearance seems to be based off that of English actor, Warwick Davis.