Greg's best friend, often involved in Greg's schemes, Rowley is more naive and optimistic, enjoying age-appropriate books and activities that sometimes put him at odds with Greg's plans.

Greg’s mother, who is supportive and proud of his accomplishments, encourages him to engage with the world academically and genuinely despite their differing views on his potential.

Greg’s father, who is more passive in parenting and often skeptical of Greg's changing interests, resorts to grounding as a way to try and teach his son life lessons.

Greg's older brother is uninterested in academics and focuses mainly on his band; he frequently torments Greg but offers help when necessary.

A boy from a nearby town who contrasts Greg with his screen-free upbringing focused on reading and playing the violin, seen by Greg's mother as a potential positive influence.