Knightbrace is an oral health-themed villain who attacks children at night and forcibly performs painful and unnecessary dental and orthodontic procedures on them.
Knightbrace's true identity is Mr. Jelly. Mr. Jelly had dreamed of being a dentist all his life, but used extreme methods and was kicked out of dental school for trying to put braces on babies. He was then forced to work in his family's candy store, thus damaging kid's teeth rather than cleaning them. He thus became Knightbrace and sought out to repair the damage he'd done. Knightbrace wears a dark blue/purple costume and a large halo-shaped retainer; this causes him to speak with a lisp. He also wields an extremely large toothbrush, clubbing the KND with it and even using it to pole vault. He considers himself to be a vigilante similar to Batman, styling himself the Enamel Avenger.
- Knightbrace was voiced by Tom Kenny, who also voiced the Common Cold.