Horace T. Wilter is Rudy and Penny's disgruntled teacher and one of the secondary antagonists In the series. He was once arrested by the police in the season 1 episode in the Chalkzone "Secret Passages."
Mr. Wilter is your usual evil teacher stereotype: intellectually unqualified and quick to dole out punishment the children he doesn't like. Despite his incompetence, he has a high opinion of himself as a teacher and is extremely pompous. Though he once enjoyed them as a child, he now has a burning hatred for cartoons, which often put him at odds with Rudy's innate creativity. He is also shown to be a crabby man, but also fairly childish (shown by him still sleeping with a teddy bear and sucking his thumb in The Smudges)
It's implied his father drove him to hate cartoons, though he still cherishes his past, based on his reactions to his encounters with the smudges in the aforementioned episode. However his views of Rudy depend on what he does for the day, with his crabbiness only coming out when provoked.
Mr. Wilter is a tall, lanky middle-aged man with a balding head, a mustache, green eyes and a long, pointy nose. He has long, twig-like legs that are bigger than any other part of his body. His usual attire consists of a red suit jacket over a white dress shirt and red necktie, brown pants that cut off at the ankles, long white socks and brown shoes.
In his first two appearances, he had lighter hair and a much bigger nose.
Owing to his hatred of cartoons, Mr. Wilter doesn't have the best impression of the more creative Rudy, often serving as a minor antagonist toward the young cartoonist. Otherwise, Wilter is merely enforcing his class rules and assignment details, and is willing to let Rudy off so long as he just follows the rules, shown in Rudy's Story, where he accepts a small written blurb for what was intended to be a written assignment.
He'd even put aside the negative attitude he has toward Rudy at the sign of genuine good work, where he awarded Rudy's Jill-O-Lantern first place in Pumpkin Love, and again in Cleo's Secret after proving the secret in the structure.
Penny Sanchez is one of the few students Mr. Wilter thinks highly of, owing to her more studious ilk. This shown by him praising her presentation in Rudy's Story, along with her knowledge on town law in That Sinking Feeling.
In the rare instance the two crossed paths in Snap Out of Water, Wilter is not questioned the cartoony Snap and went along with the white lies Penny told him.
- Mr. Wilter is the only character does never have dot eyes.