Leopold is Gary Chalmers' assistant. He is a large, surly, snarling man.
When Principal Skinner had to be temporarily replaced, Leopold was sent to tell the children who Skinner's replacement would be. He stomped into the school's gymnasium, issued several threats, and terrified the children, making them think that he would be the replacement. He then completely changed his attitude and politely introduced the actual substitute, Ned Flanders. At this revelation, the children collectively sighed with relief.
He later introduced Marge Simpson in a similar fashion when she became a substitute teacher after all the regular teachers went on strike.
 Behind the Laughter
- He is one of the few characters on The Simpsons to have eyebrows.
- A similar gag was used in Mayored to the Mob when Leavelle starts berating his students, and makes it seem as though his students are going to fail his academy, he then suddenly tells them that they've graduated from his class.