He was voice by Richard Steven Horvitz.
After Numbuh and Numbuh 4 were arrested, Numbuh 3 was the detective solving the mysteries of the case Crayon Boy was seen working with the Delightful Children From Down the Lane, but they were soon arrested for running in the halls. He had also cut a deal with Joe Balooka and had Kuki then Joe arrested by the Hall Squad. Crayon Boy then had the Hall Squad arrest themselves. This in turn made him the only kid not in detention during lunch time. His plan succeeds, but when he asks for fifty pizza bagels, the cafeteria lady tells him that they are next week's lunch, and they are currently serving lima bean sandwiches. A sandwich is then ploped onto his tray shortly after finding after. He then rips the sandwich to pieces before crying over still not getting any pizza bagels.
He is perhaps the only villain in the show who has never faced defeat by the KND, making him the most successful villain to date of having never been punished. However while he succeeded in getting the other kids in detention so he could be the first in line in lunch, he did not succeed in getting his desired pizza bagels as that was next week's lunch.
He has an uncanny resemblance to Sideshow Bob from The Simpsons and seems to have Heterochromia, meaning his eyes have different colors. He is voiced by Richard Steven Horvitz.
His pretended psychic future drawing abilities appear to be based off the character Isaac Mendez from the NBC show Heroes as his pupils disappear when he draws out the future which is similar to what happens to Isaac when he paints the future out.
Crayon Boy appears in the KND comic "Operation: T.R.A.D.E.", revealing that his name is Oliver. He buys everyone's lunches using faux Yipper Cards trying to trade for one of Numbuh 3's pizza bagels, which are later revealed to just be pretend food.
- He is the only KND Villain in the show to not face defeat.
Adult Villains: Mr. Boss | Toiletnator | Mr. Wink and Mr. Fibb | Count Spankulot | Ice Cream Men | Gramma Stuffum | Stickybeard | Knightbrace | Common Cold | Mr. Fizz | Crazy Old Cat Lady | Professor XXXL | Chester | Mega Mom and Destructo Dad | Parent Teacher Organization of Eradicating Youngsters | Proper Patrol | Mrs. Goodwall | Mr. Mogul | Great Puttinski | Nurse Claiborne | Cheese Shogun Roquefort | Robin Food | Dodgeball Wizard | Black John Licorice
Child Villains: Madame Margaret | King Sandy | Six-Gum Gang | Interesting Twins From Beneath the Mountain | James Nixon McGarfield | Anna Worthington | Valerie | Henrietta Von Marzipan | Mushi Sanban | Windsor | Crayon Boy | Numbuh Infinity | Numbuh 48 Flavors