Principal Peter Prickly
is the principal of Third Street School and is generally a cold authority figure. However it is shown that he cares about his charges, showing leniency and kindness on occasion. He has an older brother who crops up from time to time, a rival elementary school principal; despite this similarity, Prickley's brother is significantly older and nastier. As a child he also attended Third Street Elementary, during which time he was referred to as "Petey", a name that is sometimes referenced. His ultimate dream is to be a principal at a middle school - although when offered this opportunity he accepts, but then changes his mind when he sees his replacement, the evil Dr. Slicer, putting the students down. He was shown to be pleased with this decision.

He is voiced by Dabney Coleman