Miss Agatha Trunchbull is the fictional headmistress of Crunchem Hall Primary School (or Elementary School), and the main antagonist in Roald Dahl's 1988 novel Matilda and its adaptations: the 1996 film Matilda (played by Pam Ferris), the 2011 musical, and the 2022 musical film adaptation (played by Emma Thompson).

[1] Miss Trunchbull is depicted as an unwholesome role model, a fierce tyrannical monster who "frightened the life out of pupils and teachers alike", notorious for her cruel and wildly idiosyncratic discipline, with trivial misdeeds (including simply wearing pigtails) incurring punishments up to potentially fatal physical discipline.

Miss Trunchbull is the despotic headmistress of Crunchem Hall, and her bizarre and extreme discipline is handed out over the most minor misdeeds.

Once Jennifer graduated from school and teacher training college, Agatha seized hold of Jennifer's hard-earned salary, wanting her to pay off the food she ate and the clothes she wore as a child, for the first five years of her teaching career (in the 1988 novel, she left her with a net pay of £1 per week, calling it "pocket money").

It is revealed that Miss Trunchbull is superstitious and has an intense fear of ghosts, black cats, and the supernatural in general.

Another instance involves a boy named Bruce Bogtrotter, who, after eating a piece of Ms Trunchbull's chocolate cake, is "disciplined" in front of the entire student body by being forced to eat an entire colossal chocolate cake, on stage, during a school assembly.

Due to her physically demanding lifestyle, Miss Trunchbull is described in the book as being a very imposing and muscular woman, with a neck similar to that of a buffalo, legs resembling hams, and thick, trunk-like arms.

As children, Roald Dahl and his friends played a trick on the local sweet shop owner, a "mean and loathsome" old woman named Ms. Pratchett, by putting a dead mouse in a gobstopper jar.