Jack is a 13-year-old orphan who acts as the de facto leader of his friend group in post-apocalyptic Wakefield. He frames his survival experiences through the lens of action movies and video games, turning daily chores into heroic quests. Deeply appreciative of his found family, he harbors a constant fear of losing them, which sometimes manifests as overprotectiveness.

Quint is Jack's best friend and the designated inventor of the group. Operating out of a makeshift laboratory, he designs specialized gear and traps for their survival. While naturally cautious and pragmatic, his intense scientific curiosity often overrides his fear when investigating the mysteries of the monster apocalypse.

June is an independent and highly capable survivor who actively rejects any attempts to be treated as a damsel in distress. She possesses a well-rounded skill set that allowed her to survive alone for an extended period. She retains a strong connection to her pre-apocalypse interests, particularly her love for music.

Dirk is a former school bully who has integrated into Jack's friend group as their primary physical protector. Despite his intimidating size and rough exterior, he possesses a softer side that contradicts traditional stereotypes. He contributes to the group's daily life through unexpected hobbies like gardening.

Thrull is a large, imposing creature who presents himself as a former monster hunter from another dimension. He speaks English and maintains a gregarious, friendly demeanor while interacting with the human survivors. After sustaining a leg injury, he tasks Jack and his friends with completing a mysterious, yellow-paged bestiary.

Known as the Destructor of Worlds, Rezzoch is an ancient, malevolent entity from a dimension preceding Earth's monster apocalypse. Characterized by an insatiable hunger for death, this being commands immense power and inspires terror even among other monsters. Its presence looms over the surviving characters as a legendary threat.

Bardle is an ancient monster and former conjurer who resides at Joe's Pizza with other interdimensional beings. He possesses a serious, often suspicious demeanor that contrasts with the more outgoing monsters. He serves as a primary source of lore, explaining the history of the monsters' arrival on Earth.

The Wormungulous is a massive, train-sized beast capable of tunneling rapidly underground and consuming everything in its path. Despite its destructive capabilities and terrifying appearance, it behaves largely out of confusion and fear after being abruptly transported from its native dimension to Earth.

Alfred is a typical zombie wandering the streets of Wakefield until he is captured by Jack and his friends. Instead of destroying him, the children keep him in a cage and treat him with basic respect, recognizing that he was once a human being.

Rover is a large, dog-like monster who lives with the children at their tree house fortress. He provides essential transportation around the ruined town and acts as a trusted companion during their daily excursions and monster-hunting quests.

Blarg is a formidable, intelligent monster who served as the primary threat to the children during the early days of the apocalypse. Though no longer present, his defeat earned Jack significant respect among the friendly monster community at Joe's Pizza.