Jack is a 13-year-old orphan and foster child living in a fortified treehouse in Wakefield after a monster apocalypse. Armed with a broken bat he calls his "Louisville Slicer" and treating his survival like a video game with custom "Feats of Apocalyptic Success," he uses his wits and humor to survive the dangerous new world. Having never experienced a stable home, he actively seeks to build a loyal team out of the remaining survivors.

Quint is Jack's best and only pre-apocalypse friend, known in school as a socially awkward "dork." He operates as the resident scientist and brainiac of the group, converting his home's garage into an experimental laboratory. He approaches the monster threat practically, classifying creatures and building inventive defenses rather than relying on physical combat.

Dirk is the formidable former school bully who picked on Jack and Quint before the apocalypse began. Endowed with tremendous physical strength, he survives the initial outbreak alone before unexpectedly crossing paths with his former victims. He provides the muscle for the group's scavenging missions and fortifies their defenses.

June is the former editor of the Parker Middle School Gazette and the only female character in the primary survivor group. Jack believes she is a damsel in distress trapped in the middle school, but she proves to be a highly capable, battle-hardened survivor. She uses athletic prowess and resourcefulness to fend off zombies while holding out hope that her parents will return.

Blarg is a massive, forty-foot-tall monster who prowls the streets of Wakefield. Extremely violent and notably more intelligent than the standard zombies, this creature relies on daytime hunting due to its poor low-light vision. The beast quickly develops a specific vendetta against Jack following their initial encounter.

Rover is a gigantic, mutated dog that Jack discovers while scavenging for supplies. Rather than showing aggression, the massive creature displays dog-like affection and loyalty toward the humans. Fitted with a saddle created by Quint, the beast serves as a speedy transport and fiercely protective companion for the group.

Big Mama is a heavily armored, weaponized truck that Quint modifies from his mother's regular pickup. Equipped with defenses like "Butter-Slick Slingers," the vehicle operates as a mobile fortress and essential transport for the team's scavenging missions across the monster-infested city.

The Robinsons are Jack's former foster family before the monster apocalypse. They treated Jack poorly and ultimately abandoned him without warning when the monsters first appeared, fleeing the house and leaving him entirely alone to fend for himself.