・A tall, skinny teenager with messy black hair and a scruffy grunge aesthetic. He is often seen in a signature t-shirt (sometimes with a skull), jeans, and sneakers. ・He is the drummer for his garage heavy-metal band, Löded Diper. Despite his lack of formal talent and poor grades, he dreams of rock stardom. ・The ultimate slacker. Rodrick is unmotivated, manipulative, and notorious for playing elaborate, sometimes cruel, pranks on his younger brother Greg.

・Susan is deeply concerned with what other families think of them. She constantly schemes to make the Heffleys look like the "perfect family," which frequently results in extreme embarrassment for her middle son, Greg. ・While she claims to love all her children equally, she is highly indulgent and protective of her youngest son, Manny. Conversely, she holds older sons Greg and Rodrick to incredibly strict rules. ・Despite her good intentions, she frequently fails to grasp her children's individual needs or boundaries. She often implements disastrous rules—such as forcing a "no electronics" day while tracking her kids' phones—or bans books she hasn't read.

・Despite constantly striving for a cool, popular image, Greg is physically weak, avoids exercise, and vastly prefers playing video games indoors. ・A classic antihero, Greg is frequently manipulative, petty, and eager to shift the blame to others. He often views the world as a game he needs to win, sometimes treating his friends as tools to get ahead.

・Angie is mature for her age, often acting as a foil to Greg’s fame-obsessed delusions. She despises the middle school social hierarchy and frequently lectures Greg and Rowley on how "coddling" has stopped. ・She is dedicated to the school newspaper

・Often neurotic, overly cautious, and obsessive about rules. He has high expectations for his kids but frequently misunderstands them, leading to tense or comedic parenting moments. ・ Fascinated by a massive, highly detailed miniature American Civil War battlefield that he keeps in the basement.

・ He is innocent, eager to please, and deeply devoted to his friends. He has childlike interests, such as loving the comic strip "Zoo-Wee Mama!" and playing with action figures.

・Despite his age, he is manipulative.