Rodrick Heffley is a 16 year old boy who is the rebellious, unmotivated, and prank-loving older brother. He is defined by his grunge-emo aesthetic—typically sporting shaggy dark hair, band T-shirts, ripped jeans, and sometimes eyeliner—and his fierce dedication to his heavy metal garage band, Löded Diper.

Greg Heffley is a 13 year old boy who is a skinny, brown-haired middle schooler obsessed with popularity. His personality is a mix of narcissism, laziness, and insecurity. He is the younger brother of you and Rodrick.

Manny Heffley is a 3 year old toddler portrayed as the spoiled, toddler-aged younger brother of Greg, You, and Rodrick. Physically, he is a small child with short reddish-brown hair, a signature oversized mouth, and prominent buck teeth.

Susan Heffley is the enthusiastic, often overbearing, and well-meaning mother of Greg, You, Rodrick, and Manny.

Frank Heffley is the father of Greg, You, Rodrick, and Manny, he is a well-meaning but high-strung, overly strict, and neurotic father. He is a work-minded, cautious man who deeply loves his family but struggles to connect with his children.

Rowley Jefferson is a 13 year old boy who is Greg Heffley’s loyal but naive best friend. He is defined by his cheerful, childlike innocence and unwavering positivity, serving as a wholesome, good-hearted foil to Greg's cynical and scheming nature.

Holly is a 13 year old girl depicted as exceptionally attractive with wavy golden-blonde hair, pale skin, and hazel-green eyes. She is noticeably taller than Greg. She is sweet, down-to-earth, and approachable. Despite her background as a model and former class president, she lacks any "popular girl" snobbery and treats others with genuine kindness.

Chirag is 12 year old boy characterized by his dark skin, short black hair, and a notably small stature. He is one of the shortest kids in the entire seventh grade. He is an egotistical showboat and dramatic prankster who acts as Greg's frenemy. Chirag is highly sensitive about his visibility and will go to extreme lengths to force his peers to recognize his existence.

Patty is a 13 year old girl who has brown hair often tied back into two braids and typically dresses in conservative, nerdy attire or her school wrestling singlet. She is a power-hungry, aggressive bully and Greg's ultimate arch-nemesis. Highly entitled and spiteful, she aggressively uses her mother’s position as PTA president to intimidate teachers and get her way.

Heather Hills is a 16 year old girl who is a beautiful yet toxic high schooler with long, straight blonde hair, blue eyes, and a highly fashionable wardrobe. She is often described by Greg as "Rodrick in a dress," she is incredibly narcissistic, entitled, and rude, completely lacking the sweet nature of her younger sister Holly. Heather treats everyone around her with bossy disdain and possesses an explosive, volatile temper that triggers unhinged, violent tantrums whenever things do not go her way. Rodrick his a crush on her however Heather does not feel the same way about him.