Hamstersaurus Rex Books in Order

The Hamstersaurus Rex books are school comedies with a very large problem packed into a very small pet. Sam Gibbs is a middle schooler at Horace Hotwater Middle School, where he is already dealing with the usual mess of classmates, adults who do not quite get it, and the lingering embarrassment of a failed attempt at caricature drawing. Then a classroom hamster changes everything.

The hamster gets into bodybuilding powder and mutates.

Sam names the animal Hamstersaurus Rex, or Hammie Rex for short. The name fits. Hammie Rex has tiny dinosaur arms, sharp teeth, a lizard-like tail, unusual strength, and an appetite that does not respect normal limits. Sam quickly becomes the creature’s protector, even though keeping a snack-devouring mutant hamster hidden is hard enough before it starts attracting trouble.

The first book, Hamstersaurus Rex, sets up Sam’s friendship with Hammie Rex and introduces the school world around them. Sam’s best friend Dylan, intense hamster monitor Martha Cherie, and bully Kiefer “Beefer” Vanderkoff all become part of the chaos. The stories are illustrated by Tim Miller, and the drawings suit the books’ quick gags, weird creatures, and moments when a normal school day takes a sudden turn for the ridiculous.

Each later installment gives Sam and Hammie Rex a new oversized mystery. In Hamstersaurus Rex vs. Squirrel Kong, a giant squirrel causes destruction around the school, while Hammie Rex gets blamed. Hamstersaurus Rex Gets Crushed leans into spooky school rumors, with bizarre objects and possible hauntings creating real danger. By Hamstersaurus Rex vs. the Cutepocalypse, Hammie Rex is raising three tiny mutant offspring just as cute toys begin coming to life and causing havoc in town.

A shady company called SmilesCorp links much of the bigger trouble. Its products and experiments keep turning up around Sam’s world, giving the series a loose ongoing thread beneath the individual mysteries. The books never lose sight of the smaller stuff, though, like school projects, annoying classmates, family rules, and the challenge of keeping a pet fed without wrecking everything nearby.

It is goofy, fast-moving middle grade fiction with gross snacks, mutant animals, and lots of visual comedy. Under the wild setup, Sam’s growing ability to rely on Dylan, Martha, Beefer, and Hammie Rex gives the series its steady center.