Dr. Hugo Krassman is a science teacher at George Washington High School and the main villain of the film, Kermit's Swamp Years. Krassman is devoted to gathering frogs for his biology class, and browbeats his assistant, Mary. He also takes great offense when people address him as "Mr. Krassman." His antagonism towards amphibians stems from a childhood trauma when he was being teased by his classmates. In the end, after finding out Kermit can talk, he breaks down crying remembering his traumatic childhood experience, but is visibly thrilled that he's "not a froggy-pants". He then appears to drop his antagonism to frogs.
Dr. Krassman was named as an allusion to Professor Krassman from The Muppet Movie. In the DVD audio commentary for the film, Horace D'Fly asks whether the two are related. Kermit replies that "maybe we'll find out someday."