Lady And A Scholar: Matilda is a genuinely sweet-natured kid, and never thinks of herself as superior for her brains. If she's asked anything intellectual, she will respond in a polite fashion. She really only dislikes people who are annoying or rude to her. The book carefully emphasizes this.
Took a Level in Badass: When she stands up to Trunchbull, she physically removes Agatha's arm away from her own despite the fact that not only is she an Olympian, but have made clear that she broken her arm before.
Berserk Button: Miss Trunchbull hates many things, but one thing she apparently really can't stand is pigtails.
Big Bad: Matilda's father simply cannot hope to compete with her.
Would Hurt a Child: Oh boy. She not only hurts children, she defenestrates them and locks them inside what is implied to be a (hopefully) non-lethal Iron Maiden.
Abusive Parents: Matilda's parents verbally berate her and neglect her every need.
Big Bad Wannabe: As it turns out, Agatha Trunchbull is far worse than they are.
Butt Monkey: Harry Wormwood, once Matilda works out how to get even with him without being found out.
Daytime Drama Queen: Matilda's parents are addicted to television, which is shown as one of their many character flaws. When Miss Honey goes to visit them at home, there's an American soap opera on, and Mrs. Wormwood in particular objects to being interrupted when "Willard is just about to propose to Angelica!"
Fantasy-Forbidding Father: Matilda's parents don't understand Matilda's love of books and learning, rejecting her for it. They prefer the more mundane Michael who is being coached to take over his father's company.
Fat Bastard: Matilda's mother in the book and her father in the movie.
Honest John's Dealership: Mr. Wormwood's secondhand car business. Matilda's dad is the stereotypical sleazy car salesman, even putting sawdust in the oil so that the engine will burn out and they have to come back and buy a new car. The book contains a scene in which Mr. Wormwood teaches Michael the tricks to making a lemon look better.