Mr. Halper is a janitor at Westmore Middle School. He is only mentioned in Double down when Greg says the gifted and talented program was announced as Mr. Halper's helpers when gifted and talented kids needed to go to the gifted and talented classes, to avoid normal kids from not feeling special. Greg says that he thought Mr. Halper's Helpers were volunteers who helped Mr. Halper. However, Greg quickly realized all the smartest kids in his grade were part of Mr. Halper's helpers.